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Use srcu console list iteration for console list traversal. It is
acceptable because the consoles might come and go at any time.
Strict synchronizing with console registration code would not bring
any advantage over srcu.
Document why the console_lock is still necessary. Note that this
is a preparatory change for when console_lock no longer provides
synchronization for the console list.
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20221116162152.193147-21-john.ogness@linutronix.de
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With SRCU it is now safe to traverse the console list, even if
the console_trylock() failed. However, overwriting console->seq
when console_trylock() failed is still an issue.
Switch to SRCU iteration and document remaining issue with
console->seq.
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20221116162152.193147-20-john.ogness@linutronix.de
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Use srcu console list iteration for console list traversal.
Document why the console_lock is still necessary. Note that this
is a preparatory change for when console_lock no longer provides
synchronization for the console list.
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20221116162152.193147-19-john.ogness@linutronix.de
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All users of console_is_usable() are SRCU iterators. Use the
appropriate wrapper function to locklessly read the flags.
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20221116162152.193147-18-john.ogness@linutronix.de
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Use srcu console list iteration for console list traversal.
Document why the console_lock is still necessary. Note that this
is a preparatory change for when console_lock no longer provides
synchronization for the console list.
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20221116162152.193147-17-john.ogness@linutronix.de
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Guarantee safe iteration of the console list by using SRCU.
Note that in the case of a handover, the SRCU read lock is also
released. This is documented in the function description and as
comments in the code. It is a bit tricky, but this preserves the
lockdep lock ordering for the context handing over the
console_lock:
console_lock()
| mutex_acquire(&console_lock_dep_map) <-- console lock
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console_unlock()
| console_flush_all()
| | srcu_read_lock(&console_srcu) <-- srcu lock
| | console_emit_next_record()
| | | console_lock_spinning_disable_and_check()
| | | | srcu_read_unlock(&console_srcu) <-- srcu unlock
| | | | mutex_release(&console_lock_dep_map) <-- console unlock
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20221116162152.193147-16-john.ogness@linutronix.de
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Guarantee safe iteration of the console list by using SRCU.
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Reviewed-by: Aaron Tomlin <atomlin@atomlin.com>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20221116162152.193147-15-john.ogness@linutronix.de
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Rather than using the console_lock to guarantee safe console list
traversal, use srcu console list iteration.
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20221116162152.193147-14-john.ogness@linutronix.de
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After switching to SRCU for console list iteration, some readers
will begin readings console->flags as a data race. Locklessly
reading console->flags provides a consistent value because there
is at most one CPU modifying console->flags and that CPU is
using only read-modify-write operations.
Introduce a wrapper for SRCU iterators to read console flags.
Introduce a matching wrapper to write to flags of registered
consoles. Writing to flags of registered consoles is synchronized
by the console_list_lock.
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20221116162152.193147-13-john.ogness@linutronix.de
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Currently there exist races in register_console(), where the types
of registered consoles are checked (without holding the console_lock)
and then after acquiring the console_lock, it is assumed that the list
has not changed. Also, some code that performs console_unregister()
make similar assumptions.
It might be possible to fix these races using the console_lock. But
it would require a complex analysis of all console drivers to make
sure that the console_lock is not taken in match() and setup()
callbacks. And we really prefer to split up and reduce the
responsibilities of console_lock rather than expand its complexity.
Therefore, introduce a new console_list_lock to provide full
synchronization for any console list changes.
In addition, also use console_list_lock for synchronization of
console->flags updates. All flags are either static or modified only
during the console registration. There are only two exceptions.
The first exception is CON_ENABLED, which is also modified by
console_start()/console_stop(). Therefore, these functions must
also take the console_list_lock.
The second exception is when the flags are modified by the console
driver init code before the console is registered. These will be
ignored because they are not visible to the rest of the system
via the console_drivers list.
Note that one of the various responsibilities of the console_lock is
also intended to provide console list and console->flags
synchronization. Later changes will update call sites relying on the
console_lock for these purposes. Once all call sites have been
updated, the console_lock will be relieved of synchronizing
console_list and console->flags updates.
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/87sficwokr.fsf@jogness.linutronix.de
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The console_lock is held throughout the start/show/stop procedure
to print out device/driver information about all registered
consoles. Since the console_lock is being used for multiple reasons,
explicitly document these reasons. This will be useful when the
console_lock is split into fine-grained locking.
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20221116162152.193147-11-john.ogness@linutronix.de
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show_cons_active() uses the console_lock to gather information
on registered consoles. Since the console_lock is being used for
multiple reasons, explicitly document these reasons. This will
be useful when the console_lock is split into fine-grained
locking.
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20221116162152.193147-10-john.ogness@linutronix.de
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kgdboc_earlycon_init() uses the console_lock to ensure that no consoles
are unregistered until the kgdboc_earlycon is setup. This is necessary
because the trapping of the exit() callback assumes that the exit()
callback is not called before the trap is setup.
Explicitly document this non-typical console_lock usage.
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20221116162152.193147-9-john.ogness@linutronix.de
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The initial intention of the UML kmsg_dumper is to dump the kernel
buffers to stdout if there is no console available to perform the
regular crash output.
However, if ttynull was registered as a console, no crash output was
seen. Commit e23fe90dec28 ("um: kmsg_dumper: always dump when not tty
console") tried to fix this by performing the kmsg_dump unless the
stdio console was behind /dev/console or enabled. But this allowed
kmsg dumping to occur even if other non-stdio consoles will output
the crash output. Also, a console being the driver behind
/dev/console has nothing to do with a crash scenario.
Restore the initial intention by dumping the kernel buffers to stdout
only if a non-ttynull console is registered and enabled. Also add
detailed comments so that it is clear why these rules are applied.
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20221116162152.193147-8-john.ogness@linutronix.de
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It used to be that all consoles were synchronized with respect to
which message they were printing. After commit a699449bb13b ("printk:
refactor and rework printing logic"), all consoles have their own
@seq for tracking which message they are on. That commit also changed
how the initial sequence number was chosen. Instead of choosing the
next non-printed message, it chose the sequence number of the next
message that will be added to the ringbuffer.
That change created a possibility that a non-boot console taking over
for a boot console might skip messages if the boot console was behind
and did not have a chance to catch up before being unregistered.
Since it is not known which boot console is the same device, flush
all consoles and, if necessary, start with the message of the enabled
boot console that is the furthest behind. If no boot consoles are
enabled, begin with the next message that will be added to the
ringbuffer.
Also, since boot consoles are meant to be used at boot time, handle
them the same as CON_PRINTBUFFER to ensure that no initial messages
are skipped.
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20221116162152.193147-7-john.ogness@linutronix.de
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The code to initialize @seq for a new console needs to consider
more factors when choosing an initial value. Move the code into
a helper function console_init_seq() "as is" so this code can
be expanded without causing register_console() to become too
long. A later commit will implement the additional code.
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20221116162152.193147-6-john.ogness@linutronix.de
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The @bootcon_enabled and @realcon_enabled local variables actually
represent if such console types are registered. In general there
has been a confusion about enabled vs. registered. Incorrectly
naming such variables promotes such confusion.
Rename the variables to _registered.
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20221116162152.193147-5-john.ogness@linutronix.de
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Provide an NMI-safe SRCU protected variant to walk the console list.
Note that all console fields are now set before adding the console
to the list to avoid the console becoming visible by SCRU readers
before being fully initialized.
This is a preparatory change for a new console infrastructure which
operates independent of the console BKL.
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Acked-by: Miguel Ojeda <ojeda@kernel.org>
Reviewed-by: Paul E. McKenney <paulmck@kernel.org>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20221116162152.193147-4-john.ogness@linutronix.de
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Replace the open coded single linked list with a hlist so a conversion
to SRCU protected list walks can reuse the existing primitives.
Co-developed-by: John Ogness <john.ogness@linutronix.de>
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20221116162152.193147-3-john.ogness@linutronix.de
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Unprotected list walks are not necessarily safe.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20221116162152.193147-2-john.ogness@linutronix.de
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This commit adds lockdep checks for illegal use of synchronize_srcu()
within same-type SRCU read-side critical sections and within normal
RCU read-side critical sections. It also makes synchronize_srcu()
be a no-op during early boot.
These changes bring Tiny synchronize_srcu() into line with both Tree
synchronize_srcu() and Tiny synchronize_rcu().
Signed-off-by: Zqiang <qiang1.zhang@intel.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Tested-by: John Ogness <john.ogness@linutronix.de>
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Kernels configured with CONFIG_PRINTK=n and CONFIG_SRCU=n get build
failures. This causes trouble for deep embedded systems. But given
that there are more than 25 instances of "select SRCU" in the kernel,
it is hard to believe that there are many kernels running in production
without SRCU. This commit therefore makes SRCU mandatory. The SRCU
Kconfig option remains for backwards compatibility, and will be removed
when it is no longer used.
[ paulmck: Update per kernel test robot feedback. ]
Reported-by: John Ogness <john.ogness@linutronix.de>
Reported-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Cc: <linux-arch@vger.kernel.org>
Acked-by: Randy Dunlap <rdunlap@infradead.org> # build-tested
Reviewed-by: John Ogness <john.ogness@linutronix.de>
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Provide an implementation for debug_lockdep_rcu_enabled() when
CONFIG_DEBUG_LOCK_ALLOC is not enabled. This allows code to check
if rcu lockdep debugging is available without needing an extra
check if CONFIG_DEBUG_LOCK_ALLOC is enabled.
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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Currently the NMI safety debugging is only performed on architectures
that don't support NMI-safe this_cpu_inc().
Reorder the code so that other architectures like x86 also detect bad
uses.
[ paulmck: Apply kernel test robot, Stephen Rothwell, and Zqiang feedback. ]
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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Tell about the need to protect against concurrent updaters who may
overflow the GP counter behind the current update.
Reported-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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Using the NMI-unsafe reader API from within an NMI handler is very likely
to be buggy for three reasons:
1) NMIs aren't strictly re-entrant (a pending nested NMI will execute at
the end of the current one) so it should be fine to use a non-atomic
increment here. However, breakpoints can still interrupt NMIs and if
a breakpoint callback has a reader on that same ssp, a racy increment
can happen.
2) If the only reader site for a given srcu_struct structure is in an
NMI handler, then RCU should be used instead of SRCU.
3) Because of the previous reason (2), an srcu_struct structure having
an SRCU read side critical section in an NMI handler is likely to
have another one from a task context.
For all these reasons, warn if an NMI-unsafe reader API is used from an
NMI handler.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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The s390 architecture uses either a cmpxchg loop (old systems)
or the laa add-to-memory instruction (new systems) to implement
this_cpu_add(), both of which are NMI safe. This means that the old
and more-efficient srcu_read_lock() may be used in NMI context, without
the need for srcu_read_lock_nmisafe(). Therefore, add the new Kconfig
option ARCH_HAS_NMI_SAFE_THIS_CPU_OPS to arch/s390/Kconfig, which will
cause NEED_SRCU_NMI_SAFE to be deselected, thus preserving the current
srcu_read_lock() behavior.
[ paulmck: Apply Christian Borntraeger feedback. ]
Link: https://lore.kernel.org/all/20220910221947.171557773@linutronix.de/
Suggested-by: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Suggested-by: Frederic Weisbecker <frederic@kernel.org>
Suggested-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: John Ogness <john.ogness@linutronix.de>
Cc: Petr Mladek <pmladek@suse.com>
Cc: <linux-s390@vger.kernel.org>
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The loongarch architecture uses the atomic read-modify-write
amadd instruction to implement this_cpu_add(), which is NMI safe.
This means that the old and more-efficient srcu_read_lock() may be
used in NMI context, without the need for srcu_read_lock_nmisafe().
Therefore, add the new Kconfig option ARCH_HAS_NMI_SAFE_THIS_CPU_OPS
to arch/loongarch/Kconfig, which will cause NEED_SRCU_NMI_SAFE to be
deselected, thus preserving the current srcu_read_lock() behavior.
Link: https://lore.kernel.org/all/20220910221947.171557773@linutronix.de/
Suggested-by: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Suggested-by: Frederic Weisbecker <frederic@kernel.org>
Suggested-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: WANG Xuerui <kernel@xen0n.name>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: John Ogness <john.ogness@linutronix.de>
Cc: Petr Mladek <pmladek@suse.com>
Cc: <loongarch@lists.linux.dev>
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The arm64 architecture uses either an LL/SC loop (old systems) or an LSE
stadd instruction (new systems) to implement this_cpu_add(), both of which
are NMI safe. This means that the old and more-efficient srcu_read_lock()
may be used in NMI context, without the need for srcu_read_lock_nmisafe().
Therefore, add the new Kconfig option ARCH_HAS_NMI_SAFE_THIS_CPU_OPS to
arch/arm64/Kconfig, which will cause NEED_SRCU_NMI_SAFE to be deselected,
thus preserving the current srcu_read_lock() behavior.
Link: https://lore.kernel.org/all/20220910221947.171557773@linutronix.de/
Suggested-by: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Suggested-by: Frederic Weisbecker <frederic@kernel.org>
Suggested-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: John Ogness <john.ogness@linutronix.de>
Cc: Petr Mladek <pmladek@suse.com>
Cc: <linux-arm-kernel@lists.infradead.org>
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The x86 architecture uses an add-to-memory instruction to implement
this_cpu_add(), which is NMI safe. This means that the old and
more-efficient srcu_read_lock() may be used in NMI context, without
the need for srcu_read_lock_nmisafe(). Therefore, add the new Kconfig
option ARCH_HAS_NMI_SAFE_THIS_CPU_OPS to arch/x86/Kconfig, which will
cause NEED_SRCU_NMI_SAFE to be deselected, thus preserving the current
srcu_read_lock() behavior.
Link: https://lore.kernel.org/all/20220910221947.171557773@linutronix.de/
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: John Ogness <john.ogness@linutronix.de>
Cc: Petr Mladek <pmladek@suse.com>
Cc: <x86@kernel.org>
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This commit adds runtime checks to verify that a given srcu_struct uses
consistent NMI-safe (or not) read-side primitives globally, but based
on the per-CPU data. These global checks are made by the grace-period
code that must scan the srcu_data structures anyway, and are done only
in kernels built with CONFIG_PROVE_RCU=y.
Link: https://lore.kernel.org/all/20220910221947.171557773@linutronix.de/
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: John Ogness <john.ogness@linutronix.de>
Cc: Petr Mladek <pmladek@suse.com>
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This commit adds runtime checks to verify that a given srcu_struct uses
consistent NMI-safe (or not) read-side primitives on a per-CPU basis.
Link: https://lore.kernel.org/all/20220910221947.171557773@linutronix.de/
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: John Ogness <john.ogness@linutronix.de>
Cc: Petr Mladek <pmladek@suse.com>
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On strict load-store architectures, the use of this_cpu_inc() by
srcu_read_lock() and srcu_read_unlock() is not NMI-safe in TREE SRCU.
To see this suppose that an NMI arrives in the middle of srcu_read_lock(),
just after it has read ->srcu_lock_count, but before it has written
the incremented value back to memory. If that NMI handler also does
srcu_read_lock() and srcu_read_lock() on that same srcu_struct structure,
then upon return from that NMI handler, the interrupted srcu_read_lock()
will overwrite the NMI handler's update to ->srcu_lock_count, but
leave unchanged the NMI handler's update by srcu_read_unlock() to
->srcu_unlock_count.
This can result in a too-short SRCU grace period, which can in turn
result in arbitrary memory corruption.
If the NMI handler instead interrupts the srcu_read_unlock(), this
can result in eternal SRCU grace periods, which is not much better.
This commit therefore creates a pair of new srcu_read_lock_nmisafe()
and srcu_read_unlock_nmisafe() functions, which allow SRCU readers in
both NMI handlers and in process and IRQ context. It is bad practice
to mix the existing and the new _nmisafe() primitives on the same
srcu_struct structure. Use one set or the other, not both.
Just to underline that "bad practice" point, using srcu_read_lock() at
process level and srcu_read_lock_nmisafe() in your NMI handler will not,
repeat NOT, work. If you do not immediately understand why this is the
case, please review the earlier paragraphs in this commit log.
[ paulmck: Apply kernel test robot feedback. ]
[ paulmck: Apply feedback from Randy Dunlap. ]
[ paulmck: Apply feedback from John Ogness. ]
[ paulmck: Apply feedback from Frederic Weisbecker. ]
Link: https://lore.kernel.org/all/20220910221947.171557773@linutronix.de/
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Acked-by: Randy Dunlap <rdunlap@infradead.org> # build-tested
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: John Ogness <john.ogness@linutronix.de>
Cc: Petr Mladek <pmladek@suse.com>
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NMI-safe variants of srcu_read_lock() and srcu_read_unlock() are needed
by printk(), which on many architectures entails read-modify-write
atomic operations. This commit prepares Tree SRCU for this change by
making both ->srcu_lock_count and ->srcu_unlock_count by atomic_long_t.
[ paulmck: Apply feedback from John Ogness. ]
Link: https://lore.kernel.org/all/20220910221947.171557773@linutronix.de/
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: John Ogness <john.ogness@linutronix.de>
Cc: Petr Mladek <pmladek@suse.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/crng/random
Pull more random number generator updates from Jason Donenfeld:
"This time with some large scale treewide cleanups.
The intent of this pull is to clean up the way callers fetch random
integers. The current rules for doing this right are:
- If you want a secure or an insecure random u64, use get_random_u64()
- If you want a secure or an insecure random u32, use get_random_u32()
The old function prandom_u32() has been deprecated for a while
now and is just a wrapper around get_random_u32(). Same for
get_random_int().
- If you want a secure or an insecure random u16, use get_random_u16()
- If you want a secure or an insecure random u8, use get_random_u8()
- If you want secure or insecure random bytes, use get_random_bytes().
The old function prandom_bytes() has been deprecated for a while
now and has long been a wrapper around get_random_bytes()
- If you want a non-uniform random u32, u16, or u8 bounded by a
certain open interval maximum, use prandom_u32_max()
I say "non-uniform", because it doesn't do any rejection sampling
or divisions. Hence, it stays within the prandom_*() namespace, not
the get_random_*() namespace.
I'm currently investigating a "uniform" function for 6.2. We'll see
what comes of that.
By applying these rules uniformly, we get several benefits:
- By using prandom_u32_max() with an upper-bound that the compiler
can prove at compile-time is ≤65536 or ≤256, internally
get_random_u16() or get_random_u8() is used, which wastes fewer
batched random bytes, and hence has higher throughput.
- By using prandom_u32_max() instead of %, when the upper-bound is
not a constant, division is still avoided, because
prandom_u32_max() uses a faster multiplication-based trick instead.
- By using get_random_u16() or get_random_u8() in cases where the
return value is intended to indeed be a u16 or a u8, we waste fewer
batched random bytes, and hence have higher throughput.
This series was originally done by hand while I was on an airplane
without Internet. Later, Kees and I worked on retroactively figuring
out what could be done with Coccinelle and what had to be done
manually, and then we split things up based on that.
So while this touches a lot of files, the actual amount of code that's
hand fiddled is comfortably small"
* tag 'random-6.1-rc1-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/crng/random:
prandom: remove unused functions
treewide: use get_random_bytes() when possible
treewide: use get_random_u32() when possible
treewide: use get_random_{u8,u16}() when possible, part 2
treewide: use get_random_{u8,u16}() when possible, part 1
treewide: use prandom_u32_max() when possible, part 2
treewide: use prandom_u32_max() when possible, part 1
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git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux
Pull more perf tools updates from Arnaldo Carvalho de Melo:
- Use BPF CO-RE (Compile Once, Run Everywhere) to support old kernels
when using bperf (perf BPF based counters) with cgroups.
- Support HiSilicon PCIe Performance Monitoring Unit (PMU), that
monitors bandwidth, latency, bus utilization and buffer occupancy.
Documented in Documentation/admin-guide/perf/hisi-pcie-pmu.rst.
- User space tasks can migrate between CPUs, so when tracing selected
CPUs, system-wide sideband is still needed, fix it in the setup of
Intel PT on hybrid systems.
- Fix metricgroups title message in 'perf list', it should state that
the metrics groups are to be used with the '-M' option, not '-e'.
- Sync the msr-index.h copy with the kernel sources, adding support for
using "AMD64_TSC_RATIO" in filter expressions in 'perf trace' as well
as decoding it when printing the MSR tracepoint arguments.
- Fix program header size and alignment when generating a JIT ELF in
'perf inject'.
- Add multiple new Intel PT 'perf test' entries, including a jitdump
one.
- Fix the 'perf test' entries for 'perf stat' CSV and JSON output when
running on PowerPC due to an invalid topology number in that arch.
- Fix the 'perf test' for arm_coresight failures on the ARM Juno
system.
- Fix the 'perf test' attr entry for PERF_FORMAT_LOST, adding this
option to the or expression expected in the intercepted
perf_event_open() syscall.
- Add missing condition flags ('hs', 'lo', 'vc', 'vs') for arm64 in the
'perf annotate' asm parser.
- Fix 'perf mem record -C' option processing, it was being chopped up
when preparing the underlying 'perf record -e mem-events' and thus
being ignored, requiring using '-- -C CPUs' as a workaround.
- Improvements and tidy ups for 'perf test' shell infra.
- Fix Intel PT information printing segfault in uClibc, where a NULL
format was being passed to fprintf.
* tag 'perf-tools-for-v6.1-2-2022-10-16' of git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux: (23 commits)
tools arch x86: Sync the msr-index.h copy with the kernel sources
perf auxtrace arm64: Add support for parsing HiSilicon PCIe Trace packet
perf auxtrace arm64: Add support for HiSilicon PCIe Tune and Trace device driver
perf auxtrace arm: Refactor event list iteration in auxtrace_record__init()
perf tests stat+json_output: Include sanity check for topology
perf tests stat+csv_output: Include sanity check for topology
perf intel-pt: Fix system_wide dummy event for hybrid
perf intel-pt: Fix segfault in intel_pt_print_info() with uClibc
perf test: Fix attr tests for PERF_FORMAT_LOST
perf test: test_intel_pt.sh: Add 9 tests
perf inject: Fix GEN_ELF_TEXT_OFFSET for jit
perf test: test_intel_pt.sh: Add jitdump test
perf test: test_intel_pt.sh: Tidy some alignment
perf test: test_intel_pt.sh: Print a message when skipping kernel tracing
perf test: test_intel_pt.sh: Tidy some perf record options
perf test: test_intel_pt.sh: Fix return checking again
perf: Skip and warn on unknown format 'configN' attrs
perf list: Fix metricgroups title message
perf mem: Fix -C option behavior for perf mem record
perf annotate: Add missing condition flags for arm64
...
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git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild
Pull Kbuild fixes from Masahiro Yamada:
- Fix CONFIG_DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT=y compile error for the
combination of Clang >= 14 and GAS <= 2.35.
- Drop vmlinux.bz2 from the rpm package as it just annoyingly increased
the package size.
- Fix modpost error under build environments using musl.
- Make *.ll files keep value names for easier debugging
- Fix single directory build
- Prevent RISC-V from selecting the broken DWARF5 support when Clang
and GAS are used together.
* tag 'kbuild-fixes-v6.1' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild:
lib/Kconfig.debug: Add check for non-constant .{s,u}leb128 support to DWARF5
kbuild: fix single directory build
kbuild: add -fno-discard-value-names to cmd_cc_ll_c
scripts/clang-tools: Convert clang-tidy args to list
modpost: put modpost options before argument
kbuild: Stop including vmlinux.bz2 in the rpm's
Kconfig.debug: add toolchain checks for DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT
Kconfig.debug: simplify the dependency of DEBUG_INFO_DWARF4/5
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git://git.kernel.org/pub/scm/linux/kernel/git/clk/linux
Pull more clk updates from Stephen Boyd:
"This is the final part of the clk patches for this merge window.
The clk rate range series needed another week to fully bake. Maxime
fixed the bug that broke clk notifiers and prevented this from being
included in the first pull request. He also added a unit test on top
to make sure it doesn't break so easily again. The majority of the
series fixes up how the clk_set_rate_*() APIs work, particularly
around when the rate constraints are dropped and how they move around
when reparenting clks. Overall it's a much needed improvement to the
clk rate range APIs that used to be pretty broken if you looked
sideways.
Beyond the core changes there are a few driver fixes for a compilation
issue or improper data causing clks to fail to register or have the
wrong parents. These are good to get in before the first -rc so that
the system actually boots on the affected devices"
* tag 'clk-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/clk/linux: (31 commits)
clk: tegra: Fix Tegra PWM parent clock
clk: at91: fix the build with binutils 2.27
clk: qcom: gcc-msm8660: Drop hardcoded fixed board clocks
clk: mediatek: clk-mux: Add .determine_rate() callback
clk: tests: Add tests for notifiers
clk: Update req_rate on __clk_recalc_rates()
clk: tests: Add missing test case for ranges
clk: qcom: clk-rcg2: Take clock boundaries into consideration for gfx3d
clk: Introduce the clk_hw_get_rate_range function
clk: Zero the clk_rate_request structure
clk: Stop forwarding clk_rate_requests to the parent
clk: Constify clk_has_parent()
clk: Introduce clk_core_has_parent()
clk: Switch from __clk_determine_rate to clk_core_round_rate_nolock
clk: Add our request boundaries in clk_core_init_rate_req
clk: Introduce clk_hw_init_rate_request()
clk: Move clk_core_init_rate_req() from clk_core_round_rate_nolock() to its caller
clk: Change clk_core_init_rate_req prototype
clk: Set req_rate on reparenting
clk: Take into account uncached clocks in clk_set_rate_range()
...
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git://git.samba.org/sfrench/cifs-2.6
Pull more cifs updates from Steve French:
- fix a regression in guest mounts to old servers
- improvements to directory leasing (caching directory entries safely
beyond the root directory)
- symlink improvement (reducing roundtrips needed to process symlinks)
- an lseek fix (to problem where some dir entries could be skipped)
- improved ioctl for returning more detailed information on directory
change notifications
- clarify multichannel interface query warning
- cleanup fix (for better aligning buffers using ALIGN and round_up)
- a compounding fix
- fix some uninitialized variable bugs found by Coverity and the kernel
test robot
* tag '6.1-rc-smb3-client-fixes-part2' of git://git.samba.org/sfrench/cifs-2.6:
smb3: improve SMB3 change notification support
cifs: lease key is uninitialized in two additional functions when smb1
cifs: lease key is uninitialized in smb1 paths
smb3: must initialize two ACL struct fields to zero
cifs: fix double-fault crash during ntlmssp
cifs: fix static checker warning
cifs: use ALIGN() and round_up() macros
cifs: find and use the dentry for cached non-root directories also
cifs: enable caching of directories for which a lease is held
cifs: prevent copying past input buffer boundaries
cifs: fix uninitialised var in smb2_compound_op()
cifs: improve symlink handling for smb2+
smb3: clarify multichannel warning
cifs: fix regression in very old smb1 mounts
cifs: fix skipping to incorrect offset in emit_cached_dirents
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This reverts commit 78e5a3399421 ("cpumask: fix checking valid cpu range").
syzbot is hitting WARN_ON_ONCE(cpu >= nr_cpumask_bits) warning at
cpu_max_bits_warn() [1], for commit 78e5a3399421 ("cpumask: fix checking
valid cpu range") is broken. Obviously that patch hits WARN_ON_ONCE()
when e.g. reading /proc/cpuinfo because passing "cpu + 1" instead of
"cpu" will trivially hit cpu == nr_cpumask_bits condition.
Although syzbot found this problem in linux-next.git on 2022/09/27 [2],
this problem was not fixed immediately. As a result, that patch was
sent to linux.git before the patch author recognizes this problem, and
syzbot started failing to test changes in linux.git since 2022/10/10
[3].
Andrew Jones proposed a fix for x86 and riscv architectures [4]. But
[2] and [5] indicate that affected locations are not limited to arch
code. More delay before we find and fix affected locations, less tested
kernel (and more difficult to bisect and fix) before release.
We should have inspected and fixed basically all cpumask users before
applying that patch. We should not crash kernels in order to ask
existing cpumask users to update their code, even if limited to
CONFIG_DEBUG_PER_CPU_MAPS=y case.
Link: https://syzkaller.appspot.com/bug?extid=d0fd2bf0dd6da72496dd [1]
Link: https://syzkaller.appspot.com/bug?extid=21da700f3c9f0bc40150 [2]
Link: https://syzkaller.appspot.com/bug?extid=51a652e2d24d53e75734 [3]
Link: https://lkml.kernel.org/r/20221014155845.1986223-1-ajones@ventanamicro.com [4]
Link: https://syzkaller.appspot.com/bug?extid=4d46c43d81c3bd155060 [5]
Reported-by: Andrew Jones <ajones@ventanamicro.com>
Reported-by: syzbot+d0fd2bf0dd6da72496dd@syzkaller.appspotmail.com
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Yury Norov <yury.norov@gmail.com>
Cc: Borislav Petkov <bp@alien8.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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When building with a RISC-V kernel with DWARF5 debug info using clang
and the GNU assembler, several instances of the following error appear:
/tmp/vgettimeofday-48aa35.s:2963: Error: non-constant .uleb128 is not supported
Dumping the .s file reveals these .uleb128 directives come from
.debug_loc and .debug_ranges:
.Ldebug_loc0:
.byte 4 # DW_LLE_offset_pair
.uleb128 .Lfunc_begin0-.Lfunc_begin0 # starting offset
.uleb128 .Ltmp1-.Lfunc_begin0 # ending offset
.byte 1 # Loc expr size
.byte 90 # DW_OP_reg10
.byte 0 # DW_LLE_end_of_list
.Ldebug_ranges0:
.byte 4 # DW_RLE_offset_pair
.uleb128 .Ltmp6-.Lfunc_begin0 # starting offset
.uleb128 .Ltmp27-.Lfunc_begin0 # ending offset
.byte 4 # DW_RLE_offset_pair
.uleb128 .Ltmp28-.Lfunc_begin0 # starting offset
.uleb128 .Ltmp30-.Lfunc_begin0 # ending offset
.byte 0 # DW_RLE_end_of_list
There is an outstanding binutils issue to support a non-constant operand
to .sleb128 and .uleb128 in GAS for RISC-V but there does not appear to
be any movement on it, due to concerns over how it would work with
linker relaxation.
To avoid these build errors, prevent DWARF5 from being selected when
using clang and an assembler that does not have support for these symbol
deltas, which can be easily checked in Kconfig with as-instr plus the
small test program from the dwz test suite from the binutils issue.
Link: https://sourceware.org/bugzilla/show_bug.cgi?id=27215
Link: https://github.com/ClangBuiltLinux/linux/issues/1719
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
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Commit f110e5a250e3 ("kbuild: refactor single builds of *.ko") was wrong.
KBUILD_MODULES _is_ needed for single builds.
Otherwise, "make foo/bar/baz/" does not build module objects at all.
Fixes: f110e5a250e3 ("kbuild: refactor single builds of *.ko")
Reported-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Tested-by: David Sterba <dsterba@suse.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/vbabka/slab
Pull slab hotfix from Vlastimil Babka:
"A single fix for the common-kmalloc series, for warnings on mips and
sparc64 reported by Guenter Roeck"
* tag 'slab-for-6.1-rc1-hotfix' of git://git.kernel.org/pub/scm/linux/kernel/git/vbabka/slab:
mm/slab: use kmalloc_node() for off slab freelist_idx_t array allocation
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Pull OpenRISC updates from Stafford Horne:
"I have relocated to London so not much work from me while I get
settled.
Still, OpenRISC picked up two patches in this window:
- Fix for kernel page table walking from Jann Horn
- MAINTAINER entry cleanup from Palmer Dabbelt"
* tag 'for-linus' of https://github.com/openrisc/linux:
MAINTAINERS: git://github -> https://github.com for openrisc
openrisc: Fix pagewalk usage in arch_dma_{clear, set}_uncached
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git://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci
Pull pci fix from Bjorn Helgaas:
"Revert the attempt to distribute spare resources to unconfigured
hotplug bridges at boot time.
This fixed some dock hot-add scenarios, but Jonathan Cameron reported
that it broke a topology with a multi-function device where one
function was a Switch Upstream Port and the other was an Endpoint"
* tag 'pci-v6.1-fixes-1' of git://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci:
Revert "PCI: Distribute available resources for root buses, too"
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After commit d6a71648dbc0 ("mm/slab: kmalloc: pass requests larger than
order-1 page to page allocator"), SLAB passes large ( > PAGE_SIZE * 2)
requests to buddy like SLUB does.
SLAB has been using kmalloc caches to allocate freelist_idx_t array for
off slab caches. But after the commit, freelist_size can be bigger than
KMALLOC_MAX_CACHE_SIZE.
Instead of using pointer to kmalloc cache, use kmalloc_node() and only
check if the kmalloc cache is off slab during calculate_slab_order().
If freelist_size > KMALLOC_MAX_CACHE_SIZE, no looping condition happens
as it allocates freelist_idx_t array directly from buddy.
Link: https://lore.kernel.org/all/20221014205818.GA1428667@roeck-us.net/
Reported-and-tested-by: Guenter Roeck <linux@roeck-us.net>
Fixes: d6a71648dbc0 ("mm/slab: kmalloc: pass requests larger than order-1 page to page allocator")
Signed-off-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
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Github deprecated the git:// links about a year ago, so let's move to
the https:// URLs instead.
Reported-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://github.blog/2021-09-01-improving-git-protocol-security-github/
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Signed-off-by: Stafford Horne <shorne@gmail.com>
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Change notification is a commonly supported feature by most servers,
but the current ioctl to request notification when a directory is
changed does not return the information about what changed
(even though it is returned by the server in the SMB3 change
notify response), it simply returns when there is a change.
This ioctl improves upon CIFS_IOC_NOTIFY by returning the notify
information structure which includes the name of the file(s) that
changed and why. See MS-SMB2 2.2.35 for details on the individual
filter flags and the file_notify_information structure returned.
To use this simply pass in the following (with enough space
to fit at least one file_notify_information structure)
struct __attribute__((__packed__)) smb3_notify {
uint32_t completion_filter;
bool watch_tree;
uint32_t data_len;
uint8_t data[];
} __packed;
using CIFS_IOC_NOTIFY_INFO 0xc009cf0b
or equivalently _IOWR(CIFS_IOCTL_MAGIC, 11, struct smb3_notify_info)
The ioctl will block until the server detects a change to that
directory or its subdirectories (if watch_tree is set).
Acked-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Acked-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
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cifs_open and _cifsFileInfo_put also end up with lease_key uninitialized
in smb1 mounts. It is cleaner to set lease key to zero in these
places where leases are not supported (smb1 can not return lease keys
so the field was uninitialized).
Addresses-Coverity: 1514207 ("Uninitialized scalar variable")
Addresses-Coverity: 1514331 ("Uninitialized scalar variable")
Reviewed-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Signed-off-by: Steve French <stfrench@microsoft.com>
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