On Wed, Oct 15, 2014 at 9:41 AM, Patrick Palka <[email protected]> wrote: > Instead of open-coding the equivalent cmpxchg loop we can just use > atomic_set_mask and atomic_clear_mask to atomically OR or AND > the value in &buffer->record_disabled. > > Cc: Steven Rostedt <[email protected]> > Cc: Ingo Molnar <[email protected]> > Signed-off-by: Patrick Palka <[email protected]> > --- > > NB: I have only tested this patch on x86_64 by booting with > CONFIG_RING_BUFFER_STARTUP_TEST=y. > > kernel/trace/ring_buffer.c | 16 ++-------------- > 1 file changed, 2 insertions(+), 14 deletions(-) > > diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c > index 2d75c94..e15ce2a 100644 > --- a/kernel/trace/ring_buffer.c > +++ b/kernel/trace/ring_buffer.c > @@ -3050,13 +3050,7 @@ EXPORT_SYMBOL_GPL(ring_buffer_record_enable); > */ > void ring_buffer_record_off(struct ring_buffer *buffer) > { > - unsigned int rd; > - unsigned int new_rd; > - > - do { > - rd = atomic_read(&buffer->record_disabled); > - new_rd = rd | RB_BUFFER_OFF; > - } while (atomic_cmpxchg(&buffer->record_disabled, rd, new_rd) != rd); > + atomic_set_mask(RB_BUFFER_OFF, &buffer->record_disabled); > } > EXPORT_SYMBOL_GPL(ring_buffer_record_off); > > @@ -3073,13 +3067,7 @@ EXPORT_SYMBOL_GPL(ring_buffer_record_off); > */ > void ring_buffer_record_on(struct ring_buffer *buffer) > { > - unsigned int rd; > - unsigned int new_rd; > - > - do { > - rd = atomic_read(&buffer->record_disabled); > - new_rd = rd & ~RB_BUFFER_OFF; > - } while (atomic_cmpxchg(&buffer->record_disabled, rd, new_rd) != rd); > + atomic_clear_mask(RB_BUFFER_OFF, &buffer->record_disabled); > } > EXPORT_SYMBOL_GPL(ring_buffer_record_on); > > -- > 2.1.2.443.g670a3c1 >
It just occurred to me that atomic_clear_mask and atomic_set_mask expect to take an int *, not an atomic_t *, so this patch is bogus... Sorry for the noise. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
