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* [dpdk-dev] [PATCH] ipc: fix locking while sending messages
@ 2018-06-27  9:44 Anatoly Burakov
  2018-06-27 12:25 ` Zhang, Qi Z
  0 siblings, 1 reply; 3+ messages in thread
From: Anatoly Burakov @ 2018-06-27  9:44 UTC (permalink / raw)
  To: dev; +Cc: qi.z.zhang, stable

Previously, we were putting an exclusive lock to prevent secondary
processes spinning up while we are sending our messages. However,
using exclusive locks had an effect of disallowing multiple
simultaenous unrelated messages/requests being sent, which was
not the intention behind locking.

Fix it to put a shared lock on the directory. That way, we still
prevent secondary process initializations while sending data over
IPC, but allow multiple unrelated transmissions to proceed.

Fixes: 89f1fe7e6d95 ("eal: lock IPC directory on init and send")
Cc: stable@dpdk.org

Signed-off-by: Anatoly Burakov <anatoly.burakov@intel.com>
---

Notes:
    This patch is needed for multiprocess hotplug support [1], to avoid cases
    where multiple requests deadlock while in progress.
    
    [1] http://patches.dpdk.org/project/dpdk/list/?series=252

 lib/librte_eal/common/eal_common_proc.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/lib/librte_eal/common/eal_common_proc.c b/lib/librte_eal/common/eal_common_proc.c
index 707d8ab30..f010ef59e 100644
--- a/lib/librte_eal/common/eal_common_proc.c
+++ b/lib/librte_eal/common/eal_common_proc.c
@@ -786,7 +786,7 @@ mp_send(struct rte_mp_msg *msg, const char *peer, int type)
 
 	dir_fd = dirfd(mp_dir);
 	/* lock the directory to prevent processes spinning up while we send */
-	if (flock(dir_fd, LOCK_EX)) {
+	if (flock(dir_fd, LOCK_SH)) {
 		RTE_LOG(ERR, EAL, "Unable to lock directory %s\n",
 			mp_dir_path);
 		rte_errno = errno;
@@ -1020,7 +1020,7 @@ rte_mp_request_sync(struct rte_mp_msg *req, struct rte_mp_reply *reply,
 
 	dir_fd = dirfd(mp_dir);
 	/* lock the directory to prevent processes spinning up while we send */
-	if (flock(dir_fd, LOCK_EX)) {
+	if (flock(dir_fd, LOCK_SH)) {
 		RTE_LOG(ERR, EAL, "Unable to lock directory %s\n",
 			mp_dir_path);
 		closedir(mp_dir);
@@ -1146,7 +1146,7 @@ rte_mp_request_async(struct rte_mp_msg *req, const struct timespec *ts,
 	dir_fd = dirfd(mp_dir);
 
 	/* lock the directory to prevent processes spinning up while we send */
-	if (flock(dir_fd, LOCK_EX)) {
+	if (flock(dir_fd, LOCK_SH)) {
 		RTE_LOG(ERR, EAL, "Unable to lock directory %s\n",
 			mp_dir_path);
 		rte_errno = errno;
-- 
2.17.1

^ permalink raw reply	[flat|nested] 3+ messages in thread

end of thread, other threads:[~2018-06-29  0:02 UTC | newest]

Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2018-06-27  9:44 [dpdk-dev] [PATCH] ipc: fix locking while sending messages Anatoly Burakov
2018-06-27 12:25 ` Zhang, Qi Z
2018-06-29  0:02   ` [dpdk-dev] [dpdk-stable] " Thomas Monjalon

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