linux-kernel - [PATCH] rcu: Skip additional checks if rcu_cpu_stall

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Date:   Tue,  8 Aug 2017 22:50:26 +0530
From:   Neeraj Upadhyay <neeraju@...eaurora.org>
To:     paulmck@...ux.vnet.ibm.com, josh@...htriplett.org,
        rostedt@...dmis.org, mathieu.desnoyers@...icios.com,
        jiangshanlai@...il.com
Cc:     linux-kernel@...r.kernel.org,
        Neeraj Upadhyay <neeraju@...eaurora.org>
Subject: [PATCH] rcu: Skip additional checks if rcu_cpu_stall_suppress is set

If rcu_kick_kthreads is set, and gp is in progress, check_cpu_stall()
does checks to figure out whether jiffies is past rsp->jiffies_stall,
doing ordered accesses to avoid any false positives for new grace
period initialization after a sufficiently large idle period. This
extra processing can be skipped if rcu_cpu_stall_suppress is set.

Fixes: 8c7c4829a81c ("rcu: Awaken grace-period kthread if too long since FQS")
Signed-off-by: Neeraj Upadhyay <neeraju@...eaurora.org>
---
 kernel/rcu/tree.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 51d4c3a..91b7552 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -1562,10 +1562,13 @@ static void check_cpu_stall(struct rcu_state *rsp, struct rcu_data *rdp)
 	unsigned long js;
 	struct rcu_node *rnp;
 
-	if ((rcu_cpu_stall_suppress && !rcu_kick_kthreads) ||
-	    !rcu_gp_in_progress(rsp))
+	if (!rcu_gp_in_progress(rsp))
 		return;
 	rcu_stall_kick_kthreads(rsp);
+
+	if (rcu_cpu_stall_suppress)
+		return;
+
 	j = jiffies;
 
 	/*
-- 
QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a
member of the Code Aurora Forum, hosted by The Linux Foundation