X-Git-Url: http://git.liburcu.org/?a=blobdiff_plain;f=libringbuffer%2Fring_buffer_frontend.c;h=908539a8663973fde0a8e51384907b4690b0e30d;hb=8002ea62058fd7e44575f7056a26c6b257948d03;hp=45d46054cf45b2e6b4025a2f15e068068968a1f8;hpb=5ea386c3b8e3566ec0b6710c82aae433de4d944a;p=lttng-ust.git

diff --git a/libringbuffer/ring_buffer_frontend.c b/libringbuffer/ring_buffer_frontend.c
index 45d46054..908539a8 100644
--- a/libringbuffer/ring_buffer_frontend.c
+++ b/libringbuffer/ring_buffer_frontend.c
@@ -74,10 +74,6 @@
 #include "tlsfixup.h"
 #include "../liblttng-ust/compat.h"	/* For ENODATA */
 
-#ifndef max
-#define max(a, b)	((a) > (b) ? (a) : (b))
-#endif
-
 /* Print DBG() messages about events lost only every 1048576 hits */
 #define DBG_PRINT_NR_LOST	(1UL << 20)
 
@@ -164,10 +160,14 @@ static struct timer_signal_data timer_signal = {
 void lib_ring_buffer_reset(struct lttng_ust_lib_ring_buffer *buf,
 			   struct lttng_ust_shm_handle *handle)
 {
-	struct channel *chan = shmp(handle, buf->backend.chan);
-	const struct lttng_ust_lib_ring_buffer_config *config = &chan->backend.config;
+	struct channel *chan;
+	const struct lttng_ust_lib_ring_buffer_config *config;
 	unsigned int i;
 
+	chan = shmp(handle, buf->backend.chan);
+	if (!chan)
+		abort();
+	config = &chan->backend.config;
 	/*
 	 * Reset iterator first. It will put the subbuffer if it currently holds
 	 * it.
@@ -400,6 +400,9 @@ void lib_ring_buffer_channel_switch_timer(int sig, siginfo_t *si, void *uc)
 		for_each_possible_cpu(cpu) {
 			struct lttng_ust_lib_ring_buffer *buf =
 				shmp(handle, chan->backend.buf[cpu].shmp);
+
+			if (!buf)
+				abort();
 			if (uatomic_read(&buf->active_readers))
 				lib_ring_buffer_switch_slow(buf, SWITCH_ACTIVE,
 					chan->handle);
@@ -408,6 +411,8 @@ void lib_ring_buffer_channel_switch_timer(int sig, siginfo_t *si, void *uc)
 		struct lttng_ust_lib_ring_buffer *buf =
 			shmp(handle, chan->backend.buf[0].shmp);
 
+		if (!buf)
+			abort();
 		if (uatomic_read(&buf->active_readers))
 			lib_ring_buffer_switch_slow(buf, SWITCH_ACTIVE,
 				chan->handle);
@@ -435,6 +440,8 @@ void lib_ring_buffer_channel_do_read(struct channel *chan)
 			struct lttng_ust_lib_ring_buffer *buf =
 				shmp(handle, chan->backend.buf[cpu].shmp);
 
+			if (!buf)
+				abort();
 			if (uatomic_read(&buf->active_readers)
 			    && lib_ring_buffer_poll_deliver(config, buf,
 					chan, handle)) {
@@ -445,6 +452,8 @@ void lib_ring_buffer_channel_do_read(struct channel *chan)
 		struct lttng_ust_lib_ring_buffer *buf =
 			shmp(handle, chan->backend.buf[0].shmp);
 
+		if (!buf)
+			abort();
 		if (uatomic_read(&buf->active_readers)
 		    && lib_ring_buffer_poll_deliver(config, buf,
 				chan, handle)) {
@@ -629,7 +638,7 @@ void lib_ring_buffer_channel_switch_timer_start(struct channel *chan)
 	}
 
 	its.it_value.tv_sec = chan->switch_timer_interval / 1000000;
-	its.it_value.tv_nsec = chan->switch_timer_interval % 1000000;
+	its.it_value.tv_nsec = (chan->switch_timer_interval % 1000000) * 1000;
 	its.it_interval.tv_sec = its.it_value.tv_sec;
 	its.it_interval.tv_nsec = its.it_value.tv_nsec;
 
@@ -683,7 +692,7 @@ void lib_ring_buffer_channel_read_timer_start(struct channel *chan)
 	}
 
 	its.it_value.tv_sec = chan->read_timer_interval / 1000000;
-	its.it_value.tv_nsec = chan->read_timer_interval % 1000000;
+	its.it_value.tv_nsec = (chan->read_timer_interval % 1000000) * 1000;
 	its.it_interval.tv_sec = its.it_value.tv_sec;
 	its.it_interval.tv_nsec = its.it_value.tv_nsec;
 
@@ -1479,7 +1488,8 @@ void lib_ring_buffer_print_errors(struct channel *chan,
 /*
  * lib_ring_buffer_switch_old_start: Populate old subbuffer header.
  *
- * Only executed when the buffer is finalized, in SWITCH_FLUSH.
+ * Only executed by SWITCH_FLUSH, which can be issued while tracing is
+ * active or at buffer finalization (destroy).
  */
 static
 void lib_ring_buffer_switch_old_start(struct lttng_ust_lib_ring_buffer *buf,
@@ -1653,12 +1663,14 @@ int lib_ring_buffer_try_switch_slow(enum switch_mode mode,
 		unsigned long sb_index, commit_count;
 
 		/*
-		 * We are performing a SWITCH_FLUSH. At this stage, there are no
-		 * concurrent writes into the buffer.
+		 * We are performing a SWITCH_FLUSH. There may be concurrent
+		 * writes into the buffer if e.g. invoked while performing a
+		 * snapshot on an active trace.
 		 *
-		 * The client does not save any header information.  Don't
-		 * switch empty subbuffer on finalize, because it is invalid to
-		 * deliver a completely empty subbuffer.
+		 * If the client does not save any header information
+		 * (sub-buffer header size == 0), don't switch empty subbuffer
+		 * on finalize, because it is invalid to deliver a completely
+		 * empty subbuffer.
 		 */
 		if (!config->cb.subbuffer_header_size())
 			return -1;