From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756727AbYGOW6Z (ORCPT ); Tue, 15 Jul 2008 18:58:25 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756196AbYGOW6K (ORCPT ); Tue, 15 Jul 2008 18:58:10 -0400 Received: from cantor.suse.de ([195.135.220.2]:51148 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755487AbYGOW6I (ORCPT ); Tue, 15 Jul 2008 18:58:08 -0400 From: Neil Brown To: Greg K-H , Tejun Heo Date: Wed, 16 Jul 2008 08:58:04 +1000 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-ID: <18557.11132.728439.827572@notabene.brown> Cc: linux-kernel@vger.kernel.org Subject: [PATCH/RFC] sysfs: Support sysfs_notify from atomic context with new sysfs_notify_dirent X-Mailer: VM 7.19 under Emacs 21.4.1 X-face: [Gw_3E*Gng}4rRrKRYotwlE?.2|**#s9D X-Mailing-List: linux-kernel@vger.kernel.org Hi Greg, I wonder if you would consider this patch for sysfs. It makes sysfs_notify functionality more useful to me. Thanks, NeilBrown Author: NeilBrown Date: Wed Jul 16 08:54:36 2008 +1000 Support sysfs_notify from atomic context with new sysfs_notify_dirent sysfs_notify currently takes sysfs_mutex. This means that it cannot be called in atomic context. sysfs_mutex is sometimes held over a malloc (sysfs_rename_dir) so it can block on low memory. In md I want to be able to notify on a sysfs attribute from atomic context, and I don't want to block on low memory because I could be in the writeout path for freeing memory. So: - export the "sysfs_dirent" structure along with sysfs_get, sysfs_put and sysfs_get_dirent so I can get the sysfs_dirent that I want to notify on and hold it in an md structure. - split sysfs_notify_dirent out of sysfs_notify so the sysfs_dirent can be notified on with no blocking (just a spinlock). Signed-off-by: NeilBrown diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c index 8c0e4b9..0ea8458 100644 --- a/fs/sysfs/dir.c +++ b/fs/sysfs/dir.c @@ -606,6 +606,7 @@ struct sysfs_dirent *sysfs_get_dirent(struct sysfs_dirent *parent_sd, return sd; } +EXPORT_SYMBOL_GPL(sysfs_get_dirent); static int create_dir(struct kobject *kobj, struct sysfs_dirent *parent_sd, const char *name, struct sysfs_dirent **p_sd) diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c index e7735f6..c6060e8 100644 --- a/fs/sysfs/file.c +++ b/fs/sysfs/file.c @@ -440,6 +440,22 @@ static unsigned int sysfs_poll(struct file *filp, poll_table *wait) return POLLERR|POLLPRI; } +void sysfs_notify_dirent(struct sysfs_dirent *sd) +{ + struct sysfs_open_dirent *od; + + spin_lock(&sysfs_open_dirent_lock); + + od = sd->s_attr.open; + if (od) { + atomic_inc(&od->event); + wake_up_interruptible(&od->poll); + } + + spin_unlock(&sysfs_open_dirent_lock); +} +EXPORT_SYMBOL_GPL(sysfs_notify_dirent); + void sysfs_notify(struct kobject *k, char *dir, char *attr) { struct sysfs_dirent *sd = k->sd; @@ -450,19 +466,8 @@ void sysfs_notify(struct kobject *k, char *dir, char *attr) sd = sysfs_find_dirent(sd, dir); if (sd && attr) sd = sysfs_find_dirent(sd, attr); - if (sd) { - struct sysfs_open_dirent *od; - - spin_lock(&sysfs_open_dirent_lock); - - od = sd->s_attr.open; - if (od) { - atomic_inc(&od->event); - wake_up_interruptible(&od->poll); - } - - spin_unlock(&sysfs_open_dirent_lock); - } + if (sd) + sysfs_notify_dirent(sd); mutex_unlock(&sysfs_mutex); } diff --git a/fs/sysfs/mount.c b/fs/sysfs/mount.c index 14f0023..ab343e3 100644 --- a/fs/sysfs/mount.c +++ b/fs/sysfs/mount.c @@ -16,6 +16,7 @@ #include #include #include +#include #include "sysfs.h" @@ -115,3 +116,17 @@ out_err: sysfs_dir_cachep = NULL; goto out; } + +#undef sysfs_get +struct sysfs_dirent *sysfs_get(struct sysfs_dirent *sd) +{ + return __sysfs_get(sd); +} +EXPORT_SYMBOL_GPL(sysfs_get); + +#undef sysfs_put +void sysfs_put(struct sysfs_dirent *sd) +{ + __sysfs_put(sd); +} +EXPORT_SYMBOL_GPL(sysfs_put); diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h index ce4e15f..389cb3d 100644 --- a/fs/sysfs/sysfs.h +++ b/fs/sysfs/sysfs.h @@ -123,7 +123,7 @@ int sysfs_create_subdir(struct kobject *kobj, const char *name, struct sysfs_dirent **p_sd); void sysfs_remove_subdir(struct sysfs_dirent *sd); -static inline struct sysfs_dirent *sysfs_get(struct sysfs_dirent *sd) +static inline struct sysfs_dirent *__sysfs_get(struct sysfs_dirent *sd) { if (sd) { WARN_ON(!atomic_read(&sd->s_count)); @@ -131,12 +131,14 @@ static inline struct sysfs_dirent *sysfs_get(struct sysfs_dirent *sd) } return sd; } +#define sysfs_get(sd) __sysfs_get(sd) -static inline void sysfs_put(struct sysfs_dirent *sd) +static inline void __sysfs_put(struct sysfs_dirent *sd) { if (sd && atomic_dec_and_test(&sd->s_count)) release_sysfs_dirent(sd); } +#define sysfs_put(sd) __sysfs_put(sd) /* * inode.c diff --git a/include/linux/sysfs.h b/include/linux/sysfs.h index 7858eac..3ab58db 100644 --- a/include/linux/sysfs.h +++ b/include/linux/sysfs.h @@ -78,6 +78,8 @@ struct sysfs_ops { ssize_t (*store)(struct kobject *,struct attribute *,const char *, size_t); }; +struct sysfs_dirent; + #ifdef CONFIG_SYSFS int sysfs_schedule_callback(struct kobject *kobj, void (*func)(void *), @@ -115,6 +117,11 @@ void sysfs_remove_file_from_group(struct kobject *kobj, const struct attribute *attr, const char *group); void sysfs_notify(struct kobject *kobj, char *dir, char *attr); +void sysfs_notify_dirent(struct sysfs_dirent *sd); +struct sysfs_dirent *sysfs_get_dirent(struct sysfs_dirent *parent_sd, + const unsigned char *name); +struct sysfs_dirent *sysfs_get(struct sysfs_dirent *sd); +void sysfs_put(struct sysfs_dirent *sd); extern int __must_check sysfs_init(void); @@ -215,6 +222,22 @@ static inline void sysfs_remove_file_from_group(struct kobject *kobj, static inline void sysfs_notify(struct kobject *kobj, char *dir, char *attr) { } +static inline void sysfs_notify_dirent(struct sysfs_dirent *sd) +{ +} +static inline +struct sysfs_dirent *sysfs_get_dirent(struct sysfs_dirent *parent_sd, + const unsigned char *name) +{ + return NULL; +} +static inline struct sysfs_dirent sysfs_get(struct sysfs_dirent *sd) +{ + return NULL; +} +static inline void sysfs_put(struct sysfs_dirent *sd) +{ +} static inline int __must_check sysfs_init(void) {