diff options
author | Kees Cook <keescook@chromium.org> | 2017-04-28 00:53:21 +0200 |
---|---|---|
committer | Kees Cook <keescook@chromium.org> | 2017-04-28 05:35:34 +0200 |
commit | 3a7d2fd16c57a1ef47dc2891171514231c9c7c6e (patch) | |
tree | 89837e53f2b86e76275eeca582bdfe68dacc97e5 /fs/pstore | |
parent | pstore: Fix flags to enable dumps on powerpc (diff) | |
download | linux-3a7d2fd16c57a1ef47dc2891171514231c9c7c6e.tar.xz linux-3a7d2fd16c57a1ef47dc2891171514231c9c7c6e.zip |
pstore: Solve lockdep warning by moving inode locks
Lockdep complains about a possible deadlock between mount and unlink
(which is technically impossible), but fixing this improves possible
future multiple-backend support, and keeps locking in the right order.
The lockdep warning could be triggered by unlinking a file in the
pstore filesystem:
-> #1 (&sb->s_type->i_mutex_key#14){++++++}:
lock_acquire+0xc9/0x220
down_write+0x3f/0x70
pstore_mkfile+0x1f4/0x460
pstore_get_records+0x17a/0x320
pstore_fill_super+0xa4/0xc0
mount_single+0x89/0xb0
pstore_mount+0x13/0x20
mount_fs+0xf/0x90
vfs_kern_mount+0x66/0x170
do_mount+0x190/0xd50
SyS_mount+0x90/0xd0
entry_SYSCALL_64_fastpath+0x1c/0xb1
-> #0 (&psinfo->read_mutex){+.+.+.}:
__lock_acquire+0x1ac0/0x1bb0
lock_acquire+0xc9/0x220
__mutex_lock+0x6e/0x990
mutex_lock_nested+0x16/0x20
pstore_unlink+0x3f/0xa0
vfs_unlink+0xb5/0x190
do_unlinkat+0x24c/0x2a0
SyS_unlinkat+0x16/0x30
entry_SYSCALL_64_fastpath+0x1c/0xb1
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&sb->s_type->i_mutex_key#14);
lock(&psinfo->read_mutex);
lock(&sb->s_type->i_mutex_key#14);
lock(&psinfo->read_mutex);
Reported-by: Marta Lofstedt <marta.lofstedt@intel.com>
Reported-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Diffstat (limited to 'fs/pstore')
-rw-r--r-- | fs/pstore/inode.c | 37 | ||||
-rw-r--r-- | fs/pstore/internal.h | 5 | ||||
-rw-r--r-- | fs/pstore/platform.c | 10 |
3 files changed, 36 insertions, 16 deletions
diff --git a/fs/pstore/inode.c b/fs/pstore/inode.c index 06504b69575b..792a4e5f9226 100644 --- a/fs/pstore/inode.c +++ b/fs/pstore/inode.c @@ -311,9 +311,8 @@ bool pstore_is_mounted(void) * Load it up with "size" bytes of data from "buf". * Set the mtime & ctime to the date that this record was originally stored. */ -int pstore_mkfile(struct pstore_record *record) +int pstore_mkfile(struct dentry *root, struct pstore_record *record) { - struct dentry *root = pstore_sb->s_root; struct dentry *dentry; struct inode *inode; int rc = 0; @@ -322,6 +321,8 @@ int pstore_mkfile(struct pstore_record *record) unsigned long flags; size_t size = record->size + record->ecc_notice_size; + WARN_ON(!inode_is_locked(d_inode(root))); + spin_lock_irqsave(&allpstore_lock, flags); list_for_each_entry(pos, &allpstore, list) { if (pos->record->type == record->type && @@ -336,7 +337,7 @@ int pstore_mkfile(struct pstore_record *record) return rc; rc = -ENOMEM; - inode = pstore_get_inode(pstore_sb); + inode = pstore_get_inode(root->d_sb); if (!inode) goto fail; inode->i_mode = S_IFREG | 0444; @@ -394,11 +395,9 @@ int pstore_mkfile(struct pstore_record *record) break; } - inode_lock(d_inode(root)); - dentry = d_alloc_name(root, name); if (!dentry) - goto fail_lockedalloc; + goto fail_private; inode->i_size = private->total_size = size; @@ -413,12 +412,9 @@ int pstore_mkfile(struct pstore_record *record) list_add(&private->list, &allpstore); spin_unlock_irqrestore(&allpstore_lock, flags); - inode_unlock(d_inode(root)); - return 0; -fail_lockedalloc: - inode_unlock(d_inode(root)); +fail_private: free_pstore_private(private); fail_alloc: iput(inode); @@ -427,6 +423,27 @@ fail: return rc; } +/* + * Read all the records from the persistent store. Create + * files in our filesystem. Don't warn about -EEXIST errors + * when we are re-scanning the backing store looking to add new + * error records. + */ +void pstore_get_records(int quiet) +{ + struct pstore_info *psi = psinfo; + struct dentry *root; + + if (!psi || !pstore_sb) + return; + + root = pstore_sb->s_root; + + inode_lock(d_inode(root)); + pstore_get_backend_records(psi, root, quiet); + inode_unlock(d_inode(root)); +} + static int pstore_fill_super(struct super_block *sb, void *data, int silent) { struct inode *inode; diff --git a/fs/pstore/internal.h b/fs/pstore/internal.h index af1df5a36d86..c416e653dc4f 100644 --- a/fs/pstore/internal.h +++ b/fs/pstore/internal.h @@ -25,7 +25,10 @@ extern struct pstore_info *psinfo; extern void pstore_set_kmsg_bytes(int); extern void pstore_get_records(int); -extern int pstore_mkfile(struct pstore_record *record); +extern void pstore_get_backend_records(struct pstore_info *psi, + struct dentry *root, int quiet); +extern int pstore_mkfile(struct dentry *root, + struct pstore_record *record); extern bool pstore_is_mounted(void); #endif diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c index 43b3ca5e045f..d468eec9b8a6 100644 --- a/fs/pstore/platform.c +++ b/fs/pstore/platform.c @@ -810,17 +810,17 @@ static void decompress_record(struct pstore_record *record) } /* - * Read all the records from the persistent store. Create + * Read all the records from one persistent store backend. Create * files in our filesystem. Don't warn about -EEXIST errors * when we are re-scanning the backing store looking to add new * error records. */ -void pstore_get_records(int quiet) +void pstore_get_backend_records(struct pstore_info *psi, + struct dentry *root, int quiet) { - struct pstore_info *psi = psinfo; int failed = 0; - if (!psi) + if (!psi || !root) return; mutex_lock(&psi->read_mutex); @@ -850,7 +850,7 @@ void pstore_get_records(int quiet) break; decompress_record(record); - rc = pstore_mkfile(record); + rc = pstore_mkfile(root, record); if (rc) { /* pstore_mkfile() did not take record, so free it. */ kfree(record->buf); |