linux-kernel - [PATCH v9 7/9] cgroup: make TRACE_CGROUP

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Message-Id: <20190316175812.6787-8-guro@fb.com>
Date:   Sat, 16 Mar 2019 10:58:10 -0700
From:   Roman Gushchin <guroan@...il.com>
To:     Tejun Heo <tj@...nel.org>, Oleg Nesterov <oleg@...hat.com>
Cc:     Roman Gushchin <guro@...com>, kernel-team@...com,
        cgroups@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v9 7/9] cgroup: make TRACE_CGROUP_PATH irq-safe

To use the TRACE_CGROUP_PATH() macro with css_set_lock
locked, let's make the macro irq-safe.
It's necessary in order to trace cgroup freezer state
transitions (frozen/not frozen), which are happening
with css_set_lock locked.

Signed-off-by: Roman Gushchin <guro@...com>
---
 kernel/cgroup/cgroup-internal.h | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/kernel/cgroup/cgroup-internal.h b/kernel/cgroup/cgroup-internal.h
index a195328431ce..cdfa34485022 100644
--- a/kernel/cgroup/cgroup-internal.h
+++ b/kernel/cgroup/cgroup-internal.h
@@ -27,12 +27,15 @@ extern void __init enable_debug_cgroup(void);
 #define TRACE_CGROUP_PATH(type, cgrp, ...)				\
 	do {								\
 		if (trace_cgroup_##type##_enabled()) {			\
-			spin_lock(&trace_cgroup_path_lock);		\
+			unsigned long flags;				\
+			spin_lock_irqsave(&trace_cgroup_path_lock,	\
+					  flags);			\
 			cgroup_path(cgrp, trace_cgroup_path,		\
 				    TRACE_CGROUP_PATH_LEN);		\
 			trace_cgroup_##type(cgrp, trace_cgroup_path,	\
 					    ##__VA_ARGS__);		\
-			spin_unlock(&trace_cgroup_path_lock);		\
+			spin_unlock_irqrestore(&trace_cgroup_path_lock, \
+					       flags);			\
 		}							\
 	} while (0)
 
-- 
2.20.1