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From: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
To: mcgrof@kernel.org
Cc: linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org,
	Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Subject: [PATCH] umh: Optimize 'proc_cap_handler()'
Date: Fri, 20 Oct 2017 21:33:31 +0200	[thread overview]
Message-ID: <20171020193331.7233-1-christophe.jaillet@wanadoo.fr> (raw)

If 'write' is 0, we can avoid a call to spin_lock/spin_unlock.

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
---
 kernel/umh.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/umh.c b/kernel/umh.c
index 6ff9905250ff..18e5fa4b0e71 100644
--- a/kernel/umh.c
+++ b/kernel/umh.c
@@ -537,14 +537,14 @@ static int proc_cap_handler(struct ctl_table *table, int write,
 	/*
 	 * Drop everything not in the new_cap (but don't add things)
 	 */
-	spin_lock(&umh_sysctl_lock);
 	if (write) {
+		spin_lock(&umh_sysctl_lock);
 		if (table->data == CAP_BSET)
 			usermodehelper_bset = cap_intersect(usermodehelper_bset, new_cap);
 		if (table->data == CAP_PI)
 			usermodehelper_inheritable = cap_intersect(usermodehelper_inheritable, new_cap);
+		spin_unlock(&umh_sysctl_lock);
 	}
-	spin_unlock(&umh_sysctl_lock);
 
 	return 0;
 }
-- 
2.14.1

WARNING: multiple messages have this Message-ID (diff)
From: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
To: mcgrof@kernel.org
Cc: linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org,
	Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Subject: [PATCH] umh: Optimize 'proc_cap_handler()'
Date: Fri, 20 Oct 2017 19:33:31 +0000	[thread overview]
Message-ID: <20171020193331.7233-1-christophe.jaillet@wanadoo.fr> (raw)

If 'write' is 0, we can avoid a call to spin_lock/spin_unlock.

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
---
 kernel/umh.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/umh.c b/kernel/umh.c
index 6ff9905250ff..18e5fa4b0e71 100644
--- a/kernel/umh.c
+++ b/kernel/umh.c
@@ -537,14 +537,14 @@ static int proc_cap_handler(struct ctl_table *table, int write,
 	/*
 	 * Drop everything not in the new_cap (but don't add things)
 	 */
-	spin_lock(&umh_sysctl_lock);
 	if (write) {
+		spin_lock(&umh_sysctl_lock);
 		if (table->data = CAP_BSET)
 			usermodehelper_bset = cap_intersect(usermodehelper_bset, new_cap);
 		if (table->data = CAP_PI)
 			usermodehelper_inheritable = cap_intersect(usermodehelper_inheritable, new_cap);
+		spin_unlock(&umh_sysctl_lock);
 	}
-	spin_unlock(&umh_sysctl_lock);
 
 	return 0;
 }
-- 
2.14.1


             reply	other threads:[~2017-10-20 19:34 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-10-20 19:33 Christophe JAILLET [this message]
2017-10-20 19:33 ` [PATCH] umh: Optimize 'proc_cap_handler()' Christophe JAILLET
2017-11-08  1:02 ` Luis R. Rodriguez
2017-11-08  1:02   ` Luis R. Rodriguez
2017-11-10 23:51 ` Luis R. Rodriguez
2017-11-10 23:51   ` Luis R. Rodriguez

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