From: NeilBrown <neilb@suse.de>
To: linux-raid@vger.kernel.org
Subject: [md PATCH 16/26] md/raid5: use ->lock to protect accessing raid5 sysfs attributes.
Date: Wed, 04 Feb 2015 08:42:29 +1100 [thread overview]
Message-ID: <20150203214229.3448.45933.stgit@notabene.brown> (raw)
In-Reply-To: <20150203213948.3448.80258.stgit@notabene.brown>
It is important that mddev->private isn't freed while
a sysfs attribute function is accessing it.
So use mddev->lock to protect the setting of ->private to NULL, and
take that lock when checking ->private for NULL and de-referencing it
in the sysfs access functions.
This only applies to the read ('show') side of access. Write
access will be handled separately.
Signed-off-by: NeilBrown <neilb@suse.de>
---
drivers/md/raid5.c | 44 ++++++++++++++++++++++++++++----------------
1 file changed, 28 insertions(+), 16 deletions(-)
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index dab908b2aa9a..d5b80174b3b3 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -5354,11 +5354,14 @@ static void raid5d(struct md_thread *thread)
static ssize_t
raid5_show_stripe_cache_size(struct mddev *mddev, char *page)
{
- struct r5conf *conf = mddev->private;
+ struct r5conf *conf;
+ int ret = 0;
+ spin_lock(&mddev->lock);
+ conf = mddev->private;
if (conf)
- return sprintf(page, "%d\n", conf->max_nr_stripes);
- else
- return 0;
+ ret = sprintf(page, "%d\n", conf->max_nr_stripes);
+ spin_unlock(&mddev->lock);
+ return ret;
}
int
@@ -5422,11 +5425,14 @@ raid5_stripecache_size = __ATTR(stripe_cache_size, S_IRUGO | S_IWUSR,
static ssize_t
raid5_show_preread_threshold(struct mddev *mddev, char *page)
{
- struct r5conf *conf = mddev->private;
+ struct r5conf *conf;
+ int ret = 0;
+ spin_lock(&mddev->lock);
+ conf = mddev->private;
if (conf)
- return sprintf(page, "%d\n", conf->bypass_threshold);
- else
- return 0;
+ ret = sprintf(page, "%d\n", conf->bypass_threshold);
+ spin_unlock(&mddev->lock);
+ return ret;
}
static ssize_t
@@ -5456,11 +5462,14 @@ raid5_preread_bypass_threshold = __ATTR(preread_bypass_threshold,
static ssize_t
raid5_show_skip_copy(struct mddev *mddev, char *page)
{
- struct r5conf *conf = mddev->private;
+ struct r5conf *conf;
+ int ret = 0;
+ spin_lock(&mddev->lock);
+ conf = mddev->private;
if (conf)
- return sprintf(page, "%d\n", conf->skip_copy);
- else
- return 0;
+ ret = sprintf(page, "%d\n", conf->skip_copy);
+ spin_unlock(&mddev->lock);
+ return ret;
}
static ssize_t
@@ -5512,11 +5521,14 @@ raid5_stripecache_active = __ATTR_RO(stripe_cache_active);
static ssize_t
raid5_show_group_thread_cnt(struct mddev *mddev, char *page)
{
- struct r5conf *conf = mddev->private;
+ struct r5conf *conf;
+ int ret = 0;
+ spin_lock(&mddev->lock);
+ conf = mddev->private;
if (conf)
- return sprintf(page, "%d\n", conf->worker_cnt_per_group);
- else
- return 0;
+ ret = sprintf(page, "%d\n", conf->worker_cnt_per_group);
+ spin_unlock(&mddev->lock);
+ return ret;
}
static int alloc_thread_groups(struct r5conf *conf, int cnt,
next prev parent reply other threads:[~2015-02-03 21:42 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-02-03 21:42 [md PATCH 00/26] Pending md patches NeilBrown
2015-02-03 21:42 ` [md PATCH 03/26] md/raid5: separate out the easy conditions in need_this_block NeilBrown
2015-02-03 21:42 ` [md PATCH 05/26] md/raid5: need_this_block: tidy/fix last condition NeilBrown
2015-02-03 21:42 ` [md PATCH 01/26] md: do_release_stripe(): No need to call md_wakeup_thread() twice NeilBrown
2015-02-03 21:42 ` [md PATCH 02/26] md/raid5: separate large if clause out of fetch_block() NeilBrown
2015-02-03 21:42 ` [md PATCH 04/26] md/raid5: need_this_block: start simplifying the last two conditions NeilBrown
2015-02-03 21:42 ` [md PATCH 06/26] md: rename mddev->write_lock to mddev->lock NeilBrown
2015-02-03 21:42 ` [md PATCH 15/26] md: remove need for mddev_lock() in md_seq_show() NeilBrown
2015-02-03 21:42 ` [md PATCH 09/26] md/linear: remove rcu protections in favour of suspend/resume NeilBrown
2015-02-03 21:42 ` [md PATCH 17/26] md: remove mddev_lock() from md_attr_show() NeilBrown
2015-02-03 21:42 ` [md PATCH 18/26] md: remove mddev_lock from rdev_attr_show() NeilBrown
2015-02-03 21:42 ` [md PATCH 20/26] md: tidy up set_bitmap_file NeilBrown
2015-02-03 21:42 ` [md PATCH 08/26] md: make merge_bvec_fn more robust in face of personality changes NeilBrown
2015-02-03 21:42 ` [md PATCH 11/26] md: rename ->stop to ->free NeilBrown
2015-02-03 21:42 ` [md PATCH 07/26] md: make ->congested robust against personality changes NeilBrown
2015-02-03 21:42 ` [md PATCH 14/26] md/bitmap: protect clearing of ->bitmap by mddev->lock NeilBrown
2015-02-03 21:42 ` [md PATCH 19/26] md: remove unnecessary 'buf' from get_bitmap_file NeilBrown
2015-02-03 21:42 ` NeilBrown [this message]
2015-02-03 21:42 ` [md PATCH 12/26] md: level_store: group all important changes into one place NeilBrown
2015-02-03 21:42 ` [md PATCH 13/26] md: protect ->pers changes with mddev->lock NeilBrown
2015-02-03 21:42 ` [md PATCH 10/26] md: split detach operation out from ->stop NeilBrown
2015-02-03 21:42 ` [md PATCH 26/26] md: wakeup thread upon rdev_dec_pending() NeilBrown
2015-02-03 21:42 ` [md PATCH 21/26] md: move GET_BITMAP_FILE ioctl out from mddev_lock NeilBrown
2015-02-03 21:42 ` [md PATCH 22/26] md: minor cleanup in safe_delay_store NeilBrown
2015-02-03 21:42 ` [md PATCH 25/26] md: make reconfig_mutex optional for writes to md sysfs files NeilBrown
2015-02-03 21:42 ` [md PATCH 24/26] md: move mddev_lock and related to md.h NeilBrown
2015-02-03 21:42 ` [md PATCH 23/26] md: use mddev->lock to protect updates to resync_{min, max} NeilBrown
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