From: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
To: Alasdair Kergon <agk@redhat.com>,
Mike Snitzer <snitzer@kernel.org>,
dm-devel@redhat.com
Cc: linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org,
Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Subject: [PATCH] dm-crypt: Slightly simplify crypt_set_keyring_key()
Date: Sat, 28 Jan 2023 16:43:00 +0100 [thread overview]
Message-ID: <c3d25e24503d9e625cf46e9fb4ee55f10bfdd398.1674920529.git.christophe.jaillet@wanadoo.fr> (raw)
Use strchr() instead of strpbrk() when there is only 1 element in the set
of characters to look for.
This potentially saves a few cycles.
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
---
On my machine, the diff of the .s file shows that the generated code is
the same:
-- drivers/md/dm-crypt.old.s 2023-01-28 16:28:08.968026902 +0100
++ drivers/md/dm-crypt.s 2023-01-28 16:28:32.056027335 +0100
@@ -17950,7 +17950,7 @@
call __sanitizer_cov_trace_const_cmp1 #
testb %bl, %bl # _56
jne .L928 #,
-# drivers/md/dm-crypt.c:2490: key_desc = strpbrk(key_string, ":");
+# drivers/md/dm-crypt.c:2490: key_desc = strchr(key_string, ':');
call __sanitizer_cov_trace_pc #
movl $58, %esi #,
movq %r12, %rdi # key_string,
This is done thanks to fold_builtin_strpbrk() in gcc which already
transforms such patterns.
(https://github.com/gcc-mirror/gcc/blob/master/gcc/builtins.cc#L10238)
---
drivers/md/dm-crypt.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
index 2653516bcdef..b9c41fd42e8a 100644
--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -2487,7 +2487,7 @@ static int crypt_set_keyring_key(struct crypt_config *cc, const char *key_string
}
/* look for next ':' separating key_type from key_description */
- key_desc = strpbrk(key_string, ":");
+ key_desc = strchr(key_string, ':');
if (!key_desc || key_desc == key_string || !strlen(key_desc + 1))
return -EINVAL;
--
2.34.1
reply other threads:[~2023-01-28 15:43 UTC|newest]
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