Messages in this thread Patch in this message | | | Date | Tue, 24 Mar 2020 09:16:39 -0000 | From | "tip-bot2 for Paul E. McKenney" <> | Subject | [tip: core/rcu] srcu: Fix __call_srcu()/process_srcu() datarace |
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The following commit has been merged into the core/rcu branch of tip:
Commit-ID: 7ff8b4502bc0f576450d4ecbda97fa30e8002ed1 Gitweb: https://git.kernel.org/tip/7ff8b4502bc0f576450d4ecbda97fa30e8002ed1 Author: Paul E. McKenney <paulmck@kernel.org> AuthorDate: Sun, 22 Dec 2019 19:32:54 -08:00 Committer: Paul E. McKenney <paulmck@kernel.org> CommitterDate: Thu, 20 Feb 2020 16:01:11 -08:00
srcu: Fix __call_srcu()/process_srcu() datarace
The srcu_node structure's ->srcu_gp_seq_needed_exp field is accessed locklessly, so updates must use WRITE_ONCE(). This commit therefore adds the needed WRITE_ONCE() invocations.
This data race was reported by KCSAN. Not appropriate for backporting due to failure being unlikely.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org> --- kernel/rcu/srcutree.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c index 657e6a7..b1edac9 100644 --- a/kernel/rcu/srcutree.c +++ b/kernel/rcu/srcutree.c @@ -550,7 +550,7 @@ static void srcu_gp_end(struct srcu_struct *ssp) snp->srcu_have_cbs[idx] = gpseq; rcu_seq_set_state(&snp->srcu_have_cbs[idx], 1); if (ULONG_CMP_LT(snp->srcu_gp_seq_needed_exp, gpseq)) - snp->srcu_gp_seq_needed_exp = gpseq; + WRITE_ONCE(snp->srcu_gp_seq_needed_exp, gpseq); mask = snp->srcu_data_have_cbs[idx]; snp->srcu_data_have_cbs[idx] = 0; spin_unlock_irq_rcu_node(snp); @@ -660,7 +660,7 @@ static void srcu_funnel_gp_start(struct srcu_struct *ssp, struct srcu_data *sdp, if (snp == sdp->mynode) snp->srcu_data_have_cbs[idx] |= sdp->grpmask; if (!do_norm && ULONG_CMP_LT(snp->srcu_gp_seq_needed_exp, s)) - snp->srcu_gp_seq_needed_exp = s; + WRITE_ONCE(snp->srcu_gp_seq_needed_exp, s); spin_unlock_irqrestore_rcu_node(snp, flags); }
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