linux-security-module.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Davidlohr Bueso <dave@stgolabs.net>
To: dhowells@redhat.com
Cc: linux-security-module@vger.kernel.org,
	linux-kernel@vger.kernel.org, dave@stgolabs.net,
	Davidlohr Bueso <dbueso@suse.de>
Subject: [PATCH] security, keys: Optimize barrier usage for Rmw atomic  bitops
Date: Wed, 29 Jan 2020 10:06:25 -0800	[thread overview]
Message-ID: <20200129180625.24486-1-dave@stgolabs.net> (raw)

For both set and clear_bit, we can avoid the unnecessary barriers
on non LL/SC architectures, such as x86. Instead, use the
smp_mb__{before,after}_atomic() calls.

Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
---
 security/keys/gc.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/security/keys/gc.c b/security/keys/gc.c
index 671dd730ecfc..ce7b4c22e3c4 100644
--- a/security/keys/gc.c
+++ b/security/keys/gc.c
@@ -102,7 +102,7 @@ void key_gc_keytype(struct key_type *ktype)
 
 	key_gc_dead_keytype = ktype;
 	set_bit(KEY_GC_REAPING_KEYTYPE, &key_gc_flags);
-	smp_mb();
+	smp_mb__after_atomic();
 	set_bit(KEY_GC_REAP_KEYTYPE, &key_gc_flags);
 
 	kdebug("schedule");
@@ -308,7 +308,7 @@ static void key_garbage_collector(struct work_struct *work)
 
 	if (unlikely(gc_state & KEY_GC_REAPING_DEAD_3)) {
 		kdebug("dead wake");
-		smp_mb();
+		smp_mb__before_atomic();
 		clear_bit(KEY_GC_REAPING_KEYTYPE, &key_gc_flags);
 		wake_up_bit(&key_gc_flags, KEY_GC_REAPING_KEYTYPE);
 	}
-- 
2.16.4


             reply	other threads:[~2020-01-29 18:16 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-29 18:06 Davidlohr Bueso [this message]
2020-03-20 17:09 ` [PATCH] security, keys: Optimize barrier usage for Rmw atomic bitops Davidlohr Bueso

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20200129180625.24486-1-dave@stgolabs.net \
    --to=dave@stgolabs.net \
    --cc=dbueso@suse.de \
    --cc=dhowells@redhat.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-security-module@vger.kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).