The patch titled
docs: convert kref semaphore to mutex
has been added to the -mm tree. Its filename is
docs-convert-kref-semaphore-to-mutex.patch
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: docs: convert kref semaphore to mutex
From: Daniel Walker <dwalker@xxxxxxxxxx>
Just converting this documentation semaphore reference, since we don't
want to promote semaphore usage.
Signed-off-by: Daniel Walker <dwalker@xxxxxxxxxx>
Acked-by: Corey Minyard <minyard@xxxxxxx>
Cc: Greg KH <greg@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
Documentation/kref.txt | 20 ++++++++++----------
1 file changed, 10 insertions(+), 10 deletions(-)
diff -puN Documentation/kref.txt~docs-convert-kref-semaphore-to-mutex Documentation/kref.txt
--- a/Documentation/kref.txt~docs-convert-kref-semaphore-to-mutex
+++ a/Documentation/kref.txt
@@ -141,10 +141,10 @@ The last rule (rule 3) is the nastiest o
instance, you have a list of items that are each kref-ed, and you wish
to get the first one. You can't just pull the first item off the list
and kref_get() it. That violates rule 3 because you are not already
-holding a valid pointer. You must add locks or semaphores. For
-instance:
+holding a valid pointer. You must add a mutex (or some other lock).
+For instance:
-static DECLARE_MUTEX(sem);
+static DEFINE_MUTEX(mutex);
static LIST_HEAD(q);
struct my_data
{
@@ -155,12 +155,12 @@ struct my_data
static struct my_data *get_entry()
{
struct my_data *entry = NULL;
- down(&sem);
+ mutex_lock(&mutex);
if (!list_empty(&q)) {
entry = container_of(q.next, struct my_q_entry, link);
kref_get(&entry->refcount);
}
- up(&sem);
+ mutex_unlock(&mutex);
return entry;
}
@@ -174,9 +174,9 @@ static void release_entry(struct kref *r
static void put_entry(struct my_data *entry)
{
- down(&sem);
+ mutex_lock(&mutex);
kref_put(&entry->refcount, release_entry);
- up(&sem);
+ mutex_unlock(&mutex);
}
The kref_put() return value is useful if you do not want to hold the
@@ -191,13 +191,13 @@ static void release_entry(struct kref *r
static void put_entry(struct my_data *entry)
{
- down(&sem);
+ mutex_lock(&mutex);
if (kref_put(&entry->refcount, release_entry)) {
list_del(&entry->link);
- up(&sem);
+ mutex_unlock(&mutex);
kfree(entry);
} else
- up(&sem);
+ mutex_unlock(&mutex);
}
This is really more useful if you have to call other routines as part
_
Patches currently in -mm which might be from dwalker@xxxxxxxxxx are
ps3-vuart-fix-error-path-locking.patch
driver-base-memory-semaphore-to-mutex.patch
git-dvb.patch
usb-microtek-remove-unused-semaphore.patch
prism54-remove-questionable-down_interruptible-usage.patch
git-x86.patch
page-allocator-clean-up-pcp-draining-functions-swsusp-fix.patch
page-allocator-clean-up-pcp-draining-functions-swsusp-fix-fix.patch
drivers-char-tty_ioc-remove-pty_sem.patch
drivers-isdn-i4l-isdn_ttyc-remove-write_sem.patch
unix98-allocated_ptys_lock-semaphore-to-mutex.patch
docs-kernel-locking-convert-semaphore-references.patch
stopmachine-semaphore-to-mutex.patch
stopmachine-semaphore-to-mutex-fix.patch
amiga-serial-driver-port_write_mutex-fixup.patch
docs-convert-kref-semaphore-to-mutex.patch
isapnp-driver-semaphore-to-mutex.patch
isapnp-driver-semaphore-to-mutex-fix.patch
isapnp-driver-semaphore-to-mutex-fix-fix.patch
profile-likely-unlikely-macros.patch
profile-likely-unlikely-macros-fix.patch
-
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
