From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: Mon, 19 Sep 2016 01:45:32 +0000 (-0400)
Subject: Cleanup: libringbuffer: remove duplicate shmp() invocations in slow paths
X-Git-Tag: v2.9.0-rc1~14
X-Git-Url: http://git.liburcu.org/?p=lttng-ust.git;a=commitdiff_plain;h=3d3c3833d4d119acde0a3fdb2c472aea010cd7e7

Cleanup: libringbuffer: remove duplicate shmp() invocations in slow paths

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
---

diff --git a/libringbuffer/ring_buffer_frontend.c b/libringbuffer/ring_buffer_frontend.c
index accd5dc5..e631ae3d 100644
--- a/libringbuffer/ring_buffer_frontend.c
+++ b/libringbuffer/ring_buffer_frontend.c
@@ -1609,6 +1609,7 @@ void lib_ring_buffer_switch_old_start(struct lttng_ust_lib_ring_buffer *buf,
 	const struct lttng_ust_lib_ring_buffer_config *config = &chan->backend.config;
 	unsigned long oldidx = subbuf_index(offsets->old, chan);
 	unsigned long commit_count;
+	struct commit_counters_hot *cc_hot;
 
 	config->cb.buffer_begin(buf, tsc, oldidx, handle);
 
@@ -1617,16 +1618,16 @@ void lib_ring_buffer_switch_old_start(struct lttng_ust_lib_ring_buffer *buf,
 	 * determine that the subbuffer is full.
 	 */
 	cmm_smp_wmb();
+	cc_hot = shmp_index(handle, buf->commit_hot, oldidx);
 	v_add(config, config->cb.subbuffer_header_size(),
-	      &shmp_index(handle, buf->commit_hot, oldidx)->cc);
-	commit_count = v_read(config, &shmp_index(handle, buf->commit_hot, oldidx)->cc);
+	      &cc_hot->cc);
+	commit_count = v_read(config, &cc_hot->cc);
 	/* Check if the written buffer has to be delivered */
 	lib_ring_buffer_check_deliver(config, buf, chan, offsets->old,
 				      commit_count, oldidx, handle, tsc);
 	lib_ring_buffer_write_commit_counter(config, buf, chan,
 			offsets->old + config->cb.subbuffer_header_size(),
-			commit_count, handle,
-			shmp_index(handle, buf->commit_hot, oldidx));
+			commit_count, handle, cc_hot);
 }
 
 /*
@@ -1647,6 +1648,7 @@ void lib_ring_buffer_switch_old_end(struct lttng_ust_lib_ring_buffer *buf,
 	const struct lttng_ust_lib_ring_buffer_config *config = &chan->backend.config;
 	unsigned long oldidx = subbuf_index(offsets->old - 1, chan);
 	unsigned long commit_count, padding_size, data_size;
+	struct commit_counters_hot *cc_hot;
 
 	data_size = subbuf_offset(offsets->old - 1, chan) + 1;
 	padding_size = chan->backend.subbuf_size - data_size;
@@ -1658,13 +1660,14 @@ void lib_ring_buffer_switch_old_end(struct lttng_ust_lib_ring_buffer *buf,
 	 * determine that the subbuffer is full.
 	 */
 	cmm_smp_wmb();
-	v_add(config, padding_size, &shmp_index(handle, buf->commit_hot, oldidx)->cc);
-	commit_count = v_read(config, &shmp_index(handle, buf->commit_hot, oldidx)->cc);
+	cc_hot = shmp_index(handle, buf->commit_hot, oldidx);
+	v_add(config, padding_size, &cc_hot->cc);
+	commit_count = v_read(config, &cc_hot->cc);
 	lib_ring_buffer_check_deliver(config, buf, chan, offsets->old - 1,
 				      commit_count, oldidx, handle, tsc);
 	lib_ring_buffer_write_commit_counter(config, buf, chan,
 			offsets->old + padding_size, commit_count, handle,
-			shmp_index(handle, buf->commit_hot, oldidx));
+			cc_hot);
 }
 
 /*
@@ -1684,6 +1687,7 @@ void lib_ring_buffer_switch_new_start(struct lttng_ust_lib_ring_buffer *buf,
 	const struct lttng_ust_lib_ring_buffer_config *config = &chan->backend.config;
 	unsigned long beginidx = subbuf_index(offsets->begin, chan);
 	unsigned long commit_count;
+	struct commit_counters_hot *cc_hot;
 
 	config->cb.buffer_begin(buf, tsc, beginidx, handle);
 
@@ -1694,14 +1698,14 @@ void lib_ring_buffer_switch_new_start(struct lttng_ust_lib_ring_buffer *buf,
 	cmm_smp_wmb();
 	v_add(config, config->cb.subbuffer_header_size(),
 	      &shmp_index(handle, buf->commit_hot, beginidx)->cc);
-	commit_count = v_read(config, &shmp_index(handle, buf->commit_hot, beginidx)->cc);
+	cc_hot = shmp_index(handle, buf->commit_hot, beginidx);
+	commit_count = v_read(config, &cc_hot->cc);
 	/* Check if the written buffer has to be delivered */
 	lib_ring_buffer_check_deliver(config, buf, chan, offsets->begin,
 				      commit_count, beginidx, handle, tsc);
 	lib_ring_buffer_write_commit_counter(config, buf, chan,
 			offsets->begin + config->cb.subbuffer_header_size(),
-			commit_count, handle,
-			shmp_index(handle, buf->commit_hot, beginidx));
+			commit_count, handle, cc_hot);
 }
 
 /*