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| author | Christoph Hellwig <hch@lst.de> | 2021-04-03 18:15:29 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-05-14 09:44:12 +0200 |
| commit | afa4de0926635d07a0431a27e5c2f504b9c1490d (patch) | |
| tree | 5532a2063c783be511bee9a26f9165f833c3e254 /drivers/md | |
| parent | acdf531e77f098b807ba1b177dbf167ff0621c70 (diff) | |
| download | linux-stable-afa4de0926635d07a0431a27e5c2f504b9c1490d.tar.gz linux-stable-afa4de0926635d07a0431a27e5c2f504b9c1490d.tar.bz2 linux-stable-afa4de0926635d07a0431a27e5c2f504b9c1490d.zip | |
md: split mddev_find
commit 65aa97c4d2bfd76677c211b9d03ef05a98c6d68e upstream.
Split mddev_find into a simple mddev_find that just finds an existing
mddev by the unit number, and a more complicated mddev_find that deals
with find or allocating a mddev.
This turns out to fix this bug reported by Zhao Heming.
----------------------------- snip ------------------------------
commit d3374825ce57 ("md: make devices disappear when they are no longer
needed.") introduced protection between mddev creating & removing. The
md_open shouldn't create mddev when all_mddevs list doesn't contain
mddev. With currently code logic, there will be very easy to trigger
soft lockup in non-preempt env.
Diffstat (limited to 'drivers/md')
| -rw-r--r-- | drivers/md/md.c | 24 |
1 files changed, 19 insertions, 5 deletions
diff --git a/drivers/md/md.c b/drivers/md/md.c index 660cc5440dc5..65a9d0355a03 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -649,6 +649,22 @@ EXPORT_SYMBOL_GPL(mddev_init); static struct mddev *mddev_find(dev_t unit) { + struct mddev *mddev; + + if (MAJOR(unit) != MD_MAJOR) + unit &= ~((1 << MdpMinorShift) - 1); + + spin_lock(&all_mddevs_lock); + mddev = mddev_find_locked(unit); + if (mddev) + mddev_get(mddev); + spin_unlock(&all_mddevs_lock); + + return mddev; +} + +static struct mddev *mddev_find_or_alloc(dev_t unit) +{ struct mddev *mddev, *new = NULL; if (unit && MAJOR(unit) != MD_MAJOR) @@ -5436,7 +5452,7 @@ static int md_alloc(dev_t dev, char *name) * writing to /sys/module/md_mod/parameters/new_array. */ static DEFINE_MUTEX(disks_mutex); - struct mddev *mddev = mddev_find(dev); + struct mddev *mddev = mddev_find_or_alloc(dev); struct gendisk *disk; int partitioned; int shift; @@ -6312,11 +6328,9 @@ static void autorun_devices(int part) md_probe(dev, NULL, NULL); mddev = mddev_find(dev); - if (!mddev || !mddev->gendisk) { - if (mddev) - mddev_put(mddev); + if (!mddev) break; - } + if (mddev_lock(mddev)) pr_warn("md: %s locked, cannot run\n", mdname(mddev)); else if (mddev->raid_disks || mddev->major_version |