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authorIldar Ismagilov <devix84@gmail.com>2018-01-31 20:39:53 +0100
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2018-02-21 01:21:11 +0100
commita35d13ec3686612b17771bf1abcad75d2ebd42ef (patch)
tree4a01547083b852f276e2601a2ce23ac76808ede4 /kernel/rcu
parentsrcu: Abstract function name (diff)
downloadlinux-a35d13ec3686612b17771bf1abcad75d2ebd42ef.tar.xz
linux-a35d13ec3686612b17771bf1abcad75d2ebd42ef.zip
srcu: Prevent sdp->srcu_gp_seq_needed_exp counter wrap
SRCU checks each srcu_data structure's grace-period number for counter wrap four times per cycle by default. This frequency guarantees that normal comparisons will detect potential wrap. However, the expedited grace-period number is not checked. The consquences are not too horrible (a failure to expedite a grace period when requested), but it would be good to avoid such things. This commit therefore adds this check to the expedited grace-period number. Signed-off-by: Ildar Ismagilov <devix84@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'kernel/rcu')
-rw-r--r--kernel/rcu/srcutree.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c
index 01f4a8bf0e03..bb9607baad9b 100644
--- a/kernel/rcu/srcutree.c
+++ b/kernel/rcu/srcutree.c
@@ -579,6 +579,9 @@ static void srcu_gp_end(struct srcu_struct *sp)
if (ULONG_CMP_GE(gpseq,
sdp->srcu_gp_seq_needed + 100))
sdp->srcu_gp_seq_needed = gpseq;
+ if (ULONG_CMP_GE(gpseq,
+ sdp->srcu_gp_seq_needed_exp + 100))
+ sdp->srcu_gp_seq_needed_exp = gpseq;
spin_unlock_irqrestore_rcu_node(sdp, flags);
}
}