diff options
| author | Joe Damato <jdamato@fastly.com> | 2024-12-02 18:21:02 +0000 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2024-12-03 18:25:33 -0800 |
| commit | cecc1555a8c2acd65f9d36182c28ae463db0ad7e (patch) | |
| tree | 930ffda825e12b5226112ff39232f63f7e22bec0 /net | |
| parent | af8edaeddbc52e53207d859c912b017fd9a77629 (diff) | |
net: Make napi_hash_lock irq safe
Make napi_hash_lock IRQ safe. It is used during the control path, and is
taken and released in napi_hash_add and napi_hash_del, which will
typically be called by calls to napi_enable and napi_disable.
This change avoids a deadlock in pcnet32 (and other any other drivers
which follow the same pattern):
CPU 0:
pcnet32_open
spin_lock_irqsave(&lp->lock, ...)
napi_enable
napi_hash_add <- before this executes, CPU 1 proceeds
spin_lock(napi_hash_lock)
[...]
spin_unlock_irqrestore(&lp->lock, flags);
CPU 1:
pcnet32_close
napi_disable
napi_hash_del
spin_lock(napi_hash_lock)
< INTERRUPT >
pcnet32_interrupt
spin_lock(lp->lock) <- DEADLOCK
Changing the napi_hash_lock to be IRQ safe prevents the IRQ from firing
on CPU 1 until napi_hash_lock is released, preventing the deadlock.
Cc: stable@vger.kernel.org
Fixes: 86e25f40aa1e ("net: napi: Add napi_config")
Reported-by: Guenter Roeck <linux@roeck-us.net>
Closes: https://lore.kernel.org/netdev/85dd4590-ea6b-427d-876a-1d8559c7ad82@roeck-us.net/
Suggested-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Joe Damato <jdamato@fastly.com>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20241202182103.363038-1-jdamato@fastly.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net')
| -rw-r--r-- | net/core/dev.c | 18 |
1 files changed, 12 insertions, 6 deletions
diff --git a/net/core/dev.c b/net/core/dev.c index 13d00fc10f55..45a8c3dd4a64 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -6557,18 +6557,22 @@ static void __napi_hash_add_with_id(struct napi_struct *napi, static void napi_hash_add_with_id(struct napi_struct *napi, unsigned int napi_id) { - spin_lock(&napi_hash_lock); + unsigned long flags; + + spin_lock_irqsave(&napi_hash_lock, flags); WARN_ON_ONCE(napi_by_id(napi_id)); __napi_hash_add_with_id(napi, napi_id); - spin_unlock(&napi_hash_lock); + spin_unlock_irqrestore(&napi_hash_lock, flags); } static void napi_hash_add(struct napi_struct *napi) { + unsigned long flags; + if (test_bit(NAPI_STATE_NO_BUSY_POLL, &napi->state)) return; - spin_lock(&napi_hash_lock); + spin_lock_irqsave(&napi_hash_lock, flags); /* 0..NR_CPUS range is reserved for sender_cpu use */ do { @@ -6578,7 +6582,7 @@ static void napi_hash_add(struct napi_struct *napi) __napi_hash_add_with_id(napi, napi_gen_id); - spin_unlock(&napi_hash_lock); + spin_unlock_irqrestore(&napi_hash_lock, flags); } /* Warning : caller is responsible to make sure rcu grace period @@ -6586,11 +6590,13 @@ static void napi_hash_add(struct napi_struct *napi) */ static void napi_hash_del(struct napi_struct *napi) { - spin_lock(&napi_hash_lock); + unsigned long flags; + + spin_lock_irqsave(&napi_hash_lock, flags); hlist_del_init_rcu(&napi->napi_hash_node); - spin_unlock(&napi_hash_lock); + spin_unlock_irqrestore(&napi_hash_lock, flags); } static enum hrtimer_restart napi_watchdog(struct hrtimer *timer) |