58 lines
1.9 KiB
Diff
58 lines
1.9 KiB
Diff
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From 11dcfc5e044f55941ffd3f1155bbda51ed05aff7 Mon Sep 17 00:00:00 2001
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From: hewenliang <hewenliang4@huawei.com>
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Date: Mon, 12 Aug 2019 22:30:20 +0000
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Subject: [PATCH] urcu: fix deadlock issue using SIG_RCU
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reason:
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1.use a seperate thread(cds_lfht_workqueue) to handle hash table auto resize,
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and this thread block all signal at initialization.
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2.While in urcu-signal flavor, call_rcu_thread will send SIGRCU signal to all
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the registed thread to make them do cmm_smp_mb.
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3.Based on above, call_rcu_thread and workqueue thread will trapped into a dead
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loop: where call_rcu_thread hold the rcu_registry_lock to waiting all the registed
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thread to do cmm_smp_mb, while workqueue thread nerver do cmm_smp_mb and waiting to
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get rcu_registry_lock to unregiter from rcu.
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so we should not block SIGRCU in workqueue thread to avoid the dead lock.
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Signed-off-by: hewenliang <hewenliang4@huawei.com>
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---
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src/rculfhash.c | 8 +++++++-
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1 file changed, 7 insertions(+), 1 deletion(-)
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diff --git a/src/rculfhash.c b/src/rculfhash.c
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index fed33e4..fc3d610 100644
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--- a/src/rculfhash.c
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+++ b/src/rculfhash.c
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@@ -273,6 +273,7 @@
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#include <urcu/uatomic.h>
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#include <urcu/compiler.h>
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#include <urcu/rculfhash.h>
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+#include <urcu.h>
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#include <rculfhash-internal.h>
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#include <stdio.h>
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#include <pthread.h>
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@@ -2112,7 +2113,7 @@ static void cds_lfht_worker_init(struct urcu_workqueue *workqueue,
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{
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int ret;
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sigset_t mask;
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-
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+ sigset_t set;
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/* Block signal for entire process, so only our thread processes it. */
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ret = sigfillset(&mask);
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if (ret)
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@@ -2120,6 +2121,11 @@ static void cds_lfht_worker_init(struct urcu_workqueue *workqueue,
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ret = pthread_sigmask(SIG_BLOCK, &mask, NULL);
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if (ret)
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urcu_die(ret);
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+ sigemptyset(&set);
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+ sigaddset(&set, SIGRCU);
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+ ret = pthread_sigmask(SIG_UNBLOCK, &set, NULL);
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+ if (ret)
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+ urcu_die(ret);
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}
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static void cds_lfht_init_worker(const struct rcu_flavor_struct *flavor)
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--
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2.19.1
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