From: Himangi Saraogi Date: Wed, 12 Mar 2014 16:16:46 +0000 (+0530) Subject: rcu: Protect uses of ->jiffies_stall with ACCESS_ONCE() X-Git-Tag: firefly_0821_release~176^2~3465^2~29^2^2~2^2~10 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=af952b919bf9e2cf3c4e839359cfd033d98aa011;p=firefly-linux-kernel-4.4.55.git rcu: Protect uses of ->jiffies_stall with ACCESS_ONCE() Some of the accesses to the rcu_state structure's ->jiffies_stall field are unprotected. This patch protects them with ACCESS_ONCE(). The following coccinelle script was used to acheive this: /* coccinelle script to protect uses of ->jiffies_stall with ACCESS_ONCE() */ @@ identifier a; @@ ( ACCESS_ONCE(a->jiffies_stall) | - a->jiffies_stall + ACCESS_ONCE(a->jiffies_stall) ) Signed-off-by: Himangi Saraogi Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- diff --git a/kernel/rcu/tiny_plugin.h b/kernel/rcu/tiny_plugin.h index 431528520562..858c56569127 100644 --- a/kernel/rcu/tiny_plugin.h +++ b/kernel/rcu/tiny_plugin.h @@ -144,7 +144,7 @@ static void check_cpu_stall(struct rcu_ctrlblk *rcp) return; rcp->ticks_this_gp++; j = jiffies; - js = rcp->jiffies_stall; + js = ACCESS_ONCE(rcp->jiffies_stall); if (*rcp->curtail && ULONG_CMP_GE(j, js)) { pr_err("INFO: %s stall on CPU (%lu ticks this GP) idle=%llx (t=%lu jiffies q=%ld)\n", rcp->name, rcp->ticks_this_gp, rcu_dynticks_nesting, @@ -152,17 +152,17 @@ static void check_cpu_stall(struct rcu_ctrlblk *rcp) dump_stack(); } if (*rcp->curtail && ULONG_CMP_GE(j, js)) - rcp->jiffies_stall = jiffies + + ACCESS_ONCE(rcp->jiffies_stall) = jiffies + 3 * rcu_jiffies_till_stall_check() + 3; else if (ULONG_CMP_GE(j, js)) - rcp->jiffies_stall = jiffies + rcu_jiffies_till_stall_check(); + ACCESS_ONCE(rcp->jiffies_stall) = jiffies + rcu_jiffies_till_stall_check(); } static void reset_cpu_stall_ticks(struct rcu_ctrlblk *rcp) { rcp->ticks_this_gp = 0; rcp->gp_start = jiffies; - rcp->jiffies_stall = jiffies + rcu_jiffies_till_stall_check(); + ACCESS_ONCE(rcp->jiffies_stall) = jiffies + rcu_jiffies_till_stall_check(); } static void check_cpu_stalls(void)