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>

diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 99fdda29ce4e9c932f2308898cb4086e3878a31e..8c3730a8866231259225fc7561bbf5c72a0157ce 100644 (file)
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -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.