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ring-buffer: Reuse rb_watermark_hit() for the poll logic 

The check for knowing if the poll should wait or not is basically the
exact same logic as rb_watermark_hit(). The only difference is that
rb_watermark_hit() also handles the !full case. But for the full case, the
logic is the same. Just call that instead of duplicating the code in
ring_buffer_poll_wait().

Link: https://lore.kernel.org/linux-trace-kernel/20240312131952.802267543@goodmis.org

Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
This commit is contained in:
Steven Rostedt (Google) 2024-03-12 09:19:21 -04:00
parent 8145f1c35f
commit e36f19a645
1 changed files with 7 additions and 14 deletions
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21
kernel/trace/ring_buffer.c
View File

@ -960,25 +960,18 @@ __poll_t ring_buffer_poll_wait(struct trace_buffer *buffer, int cpu,
}
if (full) {
unsigned long flags;
poll_wait(filp, &rbwork->full_waiters, poll_table);
raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags);
if (!cpu_buffer->shortest_full ||
cpu_buffer->shortest_full > full)
cpu_buffer->shortest_full = full;
raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags);
if (full_hit(buffer, cpu, full))
if (rb_watermark_hit(buffer, cpu, full))
return EPOLLIN | EPOLLRDNORM;
/*
* Only allow full_waiters_pending update to be seen after
* the shortest_full is set. If the writer sees the
* full_waiters_pending flag set, it will compare the
* amount in the ring buffer to shortest_full. If the amount
* in the ring buffer is greater than the shortest_full
* percent, it will call the irq_work handler to wake up
* this list. The irq_handler will reset shortest_full
* the shortest_full is set (in rb_watermark_hit). If the
* writer sees the full_waiters_pending flag set, it will
* compare the amount in the ring buffer to shortest_full.
* If the amount in the ring buffer is greater than the
* shortest_full percent, it will call the irq_work handler
* to wake up this list. The irq_handler will reset shortest_full
* back to zero. That's done under the reader_lock, but
* the below smp_mb() makes sure that the update to
* full_waiters_pending doesn't leak up into the above.