DPDK patches and discussions
 help / color / mirror / Atom feed
From: Phil Yang <phil.yang@arm.com>
To: thomas@monjalon.net, erik.g.carrillo@intel.com, dev@dpdk.org
Cc: jerinj@marvell.com, Honnappa.Nagarahalli@arm.com,
	drc@linux.vnet.ibm.com, Ruifeng.Wang@arm.com,
	Dharmik.Thakkar@arm.com, nd@arm.com, david.marchand@redhat.com,
	mdr@ashroe.eu, nhorman@tuxdriver.com, dodji@redhat.com,
	stable@dpdk.org
Subject: [dpdk-dev] [PATCH v3 1/4] eventdev: fix race condition on timer list counter
Date: Tue,  7 Jul 2020 19:13:20 +0800	[thread overview]
Message-ID: <1594120403-17643-1-git-send-email-phil.yang@arm.com> (raw)
In-Reply-To: <1593667604-12029-1-git-send-email-phil.yang@arm.com>

The n_poll_lcores counter and poll_lcore array are shared between lcores
and the update of these variables are out of the protection of spinlock
on each lcore timer list. The read-modify-write operations of the counter
are not atomic, so it has the potential of race condition between lcores.

Use c11 atomics with RELAXED ordering to prevent confliction.

Fixes: cc7b73ea9e3b ("eventdev: add new software timer adapter")
Cc: erik.g.carrillo@intel.com
Cc: stable@dpdk.org

Signed-off-by: Phil Yang <phil.yang@arm.com>
Reviewed-by: Dharmik Thakkar <dharmik.thakkar@arm.com>
Reviewed-by: Ruifeng Wang <ruifeng.wang@arm.com>
Acked-by: Erik Gabriel Carrillo <erik.g.carrillo@intel.com>
---
v2:
Align the code. (Erik)

 lib/librte_eventdev/rte_event_timer_adapter.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/lib/librte_eventdev/rte_event_timer_adapter.c b/lib/librte_eventdev/rte_event_timer_adapter.c
index 2321803..370ea40 100644
--- a/lib/librte_eventdev/rte_event_timer_adapter.c
+++ b/lib/librte_eventdev/rte_event_timer_adapter.c
@@ -583,6 +583,7 @@ swtim_callback(struct rte_timer *tim)
 	uint16_t nb_evs_invalid = 0;
 	uint64_t opaque;
 	int ret;
+	int n_lcores;
 
 	opaque = evtim->impl_opaque[1];
 	adapter = (struct rte_event_timer_adapter *)(uintptr_t)opaque;
@@ -605,8 +606,12 @@ swtim_callback(struct rte_timer *tim)
 				      "with immediate expiry value");
 		}
 
-		if (unlikely(rte_atomic16_test_and_set(&sw->in_use[lcore].v)))
-			sw->poll_lcores[sw->n_poll_lcores++] = lcore;
+		if (unlikely(rte_atomic16_test_and_set(&sw->in_use[lcore].v))) {
+			n_lcores = __atomic_fetch_add(&sw->n_poll_lcores, 1,
+						     __ATOMIC_RELAXED);
+			__atomic_store_n(&sw->poll_lcores[n_lcores], lcore,
+					__ATOMIC_RELAXED);
+		}
 	} else {
 		EVTIM_BUF_LOG_DBG("buffered an event timer expiry event");
 
@@ -1011,6 +1016,7 @@ __swtim_arm_burst(const struct rte_event_timer_adapter *adapter,
 	uint32_t lcore_id = rte_lcore_id();
 	struct rte_timer *tim, *tims[nb_evtims];
 	uint64_t cycles;
+	int n_lcores;
 
 #ifdef RTE_LIBRTE_EVENTDEV_DEBUG
 	/* Check that the service is running. */
@@ -1033,8 +1039,10 @@ __swtim_arm_burst(const struct rte_event_timer_adapter *adapter,
 	if (unlikely(rte_atomic16_test_and_set(&sw->in_use[lcore_id].v))) {
 		EVTIM_LOG_DBG("Adding lcore id = %u to list of lcores to poll",
 			      lcore_id);
-		sw->poll_lcores[sw->n_poll_lcores] = lcore_id;
-		++sw->n_poll_lcores;
+		n_lcores = __atomic_fetch_add(&sw->n_poll_lcores, 1,
+					     __ATOMIC_RELAXED);
+		__atomic_store_n(&sw->poll_lcores[n_lcores], lcore_id,
+				__ATOMIC_RELAXED);
 	}
 
 	ret = rte_mempool_get_bulk(sw->tim_pool, (void **)tims,
-- 
2.7.4


  parent reply	other threads:[~2020-07-07 11:14 UTC|newest]

Thread overview: 45+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-12 11:19 [dpdk-dev] [PATCH 1/3] " Phil Yang
2020-06-12 11:19 ` [dpdk-dev] [PATCH 2/3] eventdev: use c11 atomics for lcore timer armed flag Phil Yang
2020-06-23 21:01   ` Carrillo, Erik G
2020-06-28 16:12     ` Phil Yang
2020-06-23 21:20   ` Stephen Hemminger
2020-06-23 21:31     ` Carrillo, Erik G
2020-06-28 16:32       ` Phil Yang
2020-06-12 11:19 ` [dpdk-dev] [PATCH 3/3] eventdev: relax smp barriers with c11 atomics Phil Yang
2020-06-22 10:12   ` Phil Yang
2020-06-23 19:38     ` Carrillo, Erik G
2020-06-28 17:33       ` Phil Yang
2020-06-29 18:07         ` Carrillo, Erik G
2020-06-18 15:17 ` [dpdk-dev] [PATCH 1/3] eventdev: fix race condition on timer list counter Carrillo, Erik G
2020-06-18 18:25   ` Honnappa Nagarahalli
2020-06-22  9:48     ` Phil Yang
2020-07-01 11:22       ` Jerin Jacob
2020-07-02  3:28         ` Phil Yang
2020-07-02  3:26     ` Phil Yang
2020-07-02  3:56       ` Honnappa Nagarahalli
2020-07-02 21:15         ` Carrillo, Erik G
2020-07-02 21:30           ` Honnappa Nagarahalli
2020-06-22  9:09   ` Phil Yang
2020-07-02  5:26 ` [dpdk-dev] [PATCH v2 1/4] " Phil Yang
2020-07-02  5:26   ` [dpdk-dev] [PATCH v2 2/4] eventdev: use c11 atomics for lcore timer armed flag Phil Yang
2020-07-02 20:21     ` Carrillo, Erik G
2020-07-02  5:26   ` [dpdk-dev] [PATCH v2 3/4] eventdev: remove redundant code Phil Yang
2020-07-03  3:35     ` Dharmik Thakkar
2020-07-02  5:26   ` [dpdk-dev] [PATCH v2 4/4] eventdev: relax smp barriers with c11 atomics Phil Yang
2020-07-02 20:30     ` Carrillo, Erik G
2020-07-03 10:50       ` Jerin Jacob
2020-07-06 10:04     ` Thomas Monjalon
2020-07-06 15:32       ` Phil Yang
2020-07-06 15:40         ` Thomas Monjalon
2020-07-07 11:13   ` Phil Yang [this message]
2020-07-07 11:13     ` [dpdk-dev] [PATCH v3 2/4] eventdev: use C11 atomics for lcore timer armed flag Phil Yang
2020-07-07 11:13     ` [dpdk-dev] [PATCH v3 3/4] eventdev: remove redundant code Phil Yang
2020-07-07 11:13     ` [dpdk-dev] [PATCH v3 4/4] eventdev: relax smp barriers with C11 atomics Phil Yang
2020-07-07 14:29       ` Jerin Jacob
2020-07-07 15:56         ` Phil Yang
2020-07-07 15:54     ` [dpdk-dev] [PATCH v4 1/4] eventdev: fix race condition on timer list counter Phil Yang
2020-07-07 15:54       ` [dpdk-dev] [PATCH v4 2/4] eventdev: use C11 atomics for lcore timer armed flag Phil Yang
2020-07-07 15:54       ` [dpdk-dev] [PATCH v4 3/4] eventdev: remove redundant code Phil Yang
2020-07-07 15:54       ` [dpdk-dev] [PATCH v4 4/4] eventdev: relax smp barriers with C11 atomics Phil Yang
2020-07-08 13:30       ` [dpdk-dev] [PATCH v4 1/4] eventdev: fix race condition on timer list counter Jerin Jacob
2020-07-08 15:01         ` Thomas Monjalon

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=1594120403-17643-1-git-send-email-phil.yang@arm.com \
    --to=phil.yang@arm.com \
    --cc=Dharmik.Thakkar@arm.com \
    --cc=Honnappa.Nagarahalli@arm.com \
    --cc=Ruifeng.Wang@arm.com \
    --cc=david.marchand@redhat.com \
    --cc=dev@dpdk.org \
    --cc=dodji@redhat.com \
    --cc=drc@linux.vnet.ibm.com \
    --cc=erik.g.carrillo@intel.com \
    --cc=jerinj@marvell.com \
    --cc=mdr@ashroe.eu \
    --cc=nd@arm.com \
    --cc=nhorman@tuxdriver.com \
    --cc=stable@dpdk.org \
    --cc=thomas@monjalon.net \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).