fs: annotate cdev_lock with __cacheline_aligned_in_smp

mjguzik · brauner · commit 5854fc6391e9 · 2025-12-15T14:33:38.000+01:00
No need for the crapper to be susceptible to false-sharing. Signed-off-by: Mateusz Guzik <mjguzik@gmail.com> Link: https://patch.msgid.link/20251203095508.291073-1-mjguzik@gmail.com Reviewed-by: Jan Kara <jack@suse.cz> Signed-off-by: Christian Brauner <brauner@kernel.org>
diff --git a/fs/char_dev.c b/fs/char_dev.c
@@ -343,7 +343,7 @@ void __unregister_chrdev(unsigned int major, unsigned int baseminor,
 	kfree(cd);
 }
 
-static DEFINE_SPINLOCK(cdev_lock);
+static __cacheline_aligned_in_smp DEFINE_SPINLOCK(cdev_lock);
 
 static struct kobject *cdev_get(struct cdev *p)
 {

Original file line number	Diff line number	Diff line change
`@@ -343,7 +343,7 @@ void __unregister_chrdev(unsigned int major, unsigned int baseminor,`
`343`	`343`	`kfree(cd);`
`344`	`344`	`}`
`345`	`345`
`346`		`-static DEFINE_SPINLOCK(cdev_lock);`
	`346`	`+static __cacheline_aligned_in_smp DEFINE_SPINLOCK(cdev_lock);`
`347`	`347`
`348`	`348`	`static struct kobject cdev_get(struct cdev p)`
`349`	`349`	`{`