summaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorSteven Rostedt <rostedt@goodmis.org>2024-11-13 23:08:39 -0500
committerSteven Rostedt (Google) <rostedt@goodmis.org>2024-11-14 10:01:00 -0500
commit580bb355bcae7e9a6606ce9644af09b2a793f1bb (patch)
tree8874bc104727b78aaa2a4ebadb3e459be7d4b72f
parent09661f75e75cb6c1d2d8326a70c311d46729235f (diff)
Revert: "ring-buffer: Do not have boot mapped buffers hook to CPU hotplug"
A crash happened when testing cpu hotplug with respect to the memory mapped ring buffers. It was assumed that the hot plug code was adding a per CPU buffer that was already created that caused the crash. The real problem was due to ref counting and was fixed by commit 2cf9733891a4 ("ring-buffer: Fix refcount setting of boot mapped buffers"). When a per CPU buffer is created, it will not be created again even with CPU hotplug, so the fix to not use CPU hotplug was a red herring. In fact, it caused only the boot CPU buffer to be created, leaving the other CPU per CPU buffers disabled. Revert that change as it was not the culprit of the fix it was intended to be. Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Link: https://lore.kernel.org/20241113230839.6c03640f@gandalf.local.home Fixes: 912da2c384d5 ("ring-buffer: Do not have boot mapped buffers hook to CPU hotplug") Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
-rw-r--r--kernel/trace/ring_buffer.c9
1 files changed, 3 insertions, 6 deletions
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 3ea4f7bb1837..5807116bcd0b 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -2337,12 +2337,9 @@ static struct trace_buffer *alloc_buffer(unsigned long size, unsigned flags,
if (!buffer->buffers[cpu])
goto fail_free_buffers;
- /* If already mapped, do not hook to CPU hotplug */
- if (!start) {
- ret = cpuhp_state_add_instance(CPUHP_TRACE_RB_PREPARE, &buffer->node);
- if (ret < 0)
- goto fail_free_buffers;
- }
+ ret = cpuhp_state_add_instance(CPUHP_TRACE_RB_PREPARE, &buffer->node);
+ if (ret < 0)
+ goto fail_free_buffers;
mutex_init(&buffer->mutex);