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authorArtem Bityutskiy <Artem.Bityutskiy@nokia.com>2008-06-16 13:35:23 +0300
committerArtem Bityutskiy <Artem.Bityutskiy@nokia.com>2008-07-24 13:32:56 +0300
commit23add7455c42eef63f8719bd268328047d4aed69 (patch)
tree22fff61ae989e32987635e334a0b542dd6389433
parent472018f73e7308a7f29b753ee8c742b6f45f103f (diff)
UBI: fix LEB locking
leb_read_unlock() may be called simultaniously by several tasks. The would race at the following code: up_read(&le->mutex); if (free) kfree(le); And it is possible that one task frees 'le' before the other tasks do 'up_read()'. Fix this by doing up_read and free inside the 'ubi->ltree' lock. Below it the oops we had because of this: BUG: spinlock bad magic on CPU#0, integck/7504 BUG: unable to handle kernel paging request at 6b6b6c4f IP: [<c0211221>] spin_bug+0x5c/0xdb *pde = 00000000 Oops: 0000 [#1] PREEMPT SMP Modules linked in: ubifs ubi nandsim nand nand_ids nand_ecc video output Pid: 7504, comm: integck Not tainted (2.6.26-rc3ubifs26 #8) EIP: 0060:[<c0211221>] EFLAGS: 00010002 CPU: 0 EIP is at spin_bug+0x5c/0xdb EAX: 00000032 EBX: 6b6b6b6b ECX: 6b6b6b6b EDX: f7f7ce30 ESI: f76491dc EDI: c044f51f EBP: e8a736cc ESP: e8a736a8 DS: 007b ES: 007b FS: 00d8 GS: 0033 SS: 0068 Process integck (pid: 7504, ti=e8a72000 task=f7f7ce30 task.ti=e8a72000) Stack: c044f754 c044f51f 00000000 f7f7d024 00001d50 00000001 f76491dc 00000296 f6df50e0 e8a736d8 c02112f0 f76491dc e8a736e8 c039157a f7d9e830 f76491d8 e8a7370c c020b975 f76491dc 00000296 f76491f8 00000000 f76491d8 00000000 Call Trace: [<c02112f0>] ? _raw_spin_unlock+0x50/0x7c [<c039157a>] ? _spin_unlock_irqrestore+0x20/0x58 [<c020b975>] ? rwsem_wake+0x4b/0x122 [<c0390e0a>] ? call_rwsem_wake+0xa/0xc [<c0139ee7>] ? up_read+0x28/0x31 [<f8873b3c>] ? leb_read_unlock+0x73/0x7b [ubi] [<f88742a3>] ? ubi_eba_read_leb+0x195/0x2b0 [ubi] [<f8872a04>] ? ubi_leb_read+0xaf/0xf8 [ubi] Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
-rw-r--r--drivers/mtd/ubi/eba.c27
1 files changed, 7 insertions, 20 deletions
diff --git a/drivers/mtd/ubi/eba.c b/drivers/mtd/ubi/eba.c
index 623d25f4855..8dc488fc0cd 100644
--- a/drivers/mtd/ubi/eba.c
+++ b/drivers/mtd/ubi/eba.c
@@ -223,22 +223,18 @@ static int leb_read_lock(struct ubi_device *ubi, int vol_id, int lnum)
*/
static void leb_read_unlock(struct ubi_device *ubi, int vol_id, int lnum)
{
- int free = 0;
struct ubi_ltree_entry *le;
spin_lock(&ubi->ltree_lock);
le = ltree_lookup(ubi, vol_id, lnum);
le->users -= 1;
ubi_assert(le->users >= 0);
+ up_read(&le->mutex);
if (le->users == 0) {
rb_erase(&le->rb, &ubi->ltree);
- free = 1;
+ kfree(le);
}
spin_unlock(&ubi->ltree_lock);
-
- up_read(&le->mutex);
- if (free)
- kfree(le);
}
/**
@@ -274,7 +270,6 @@ static int leb_write_lock(struct ubi_device *ubi, int vol_id, int lnum)
*/
static int leb_write_trylock(struct ubi_device *ubi, int vol_id, int lnum)
{
- int free;
struct ubi_ltree_entry *le;
le = ltree_add_entry(ubi, vol_id, lnum);
@@ -289,12 +284,9 @@ static int leb_write_trylock(struct ubi_device *ubi, int vol_id, int lnum)
ubi_assert(le->users >= 0);
if (le->users == 0) {
rb_erase(&le->rb, &ubi->ltree);
- free = 1;
- } else
- free = 0;
- spin_unlock(&ubi->ltree_lock);
- if (free)
kfree(le);
+ }
+ spin_unlock(&ubi->ltree_lock);
return 1;
}
@@ -307,23 +299,18 @@ static int leb_write_trylock(struct ubi_device *ubi, int vol_id, int lnum)
*/
static void leb_write_unlock(struct ubi_device *ubi, int vol_id, int lnum)
{
- int free;
struct ubi_ltree_entry *le;
spin_lock(&ubi->ltree_lock);
le = ltree_lookup(ubi, vol_id, lnum);
le->users -= 1;
ubi_assert(le->users >= 0);
+ up_write(&le->mutex);
if (le->users == 0) {
rb_erase(&le->rb, &ubi->ltree);
- free = 1;
- } else
- free = 0;
- spin_unlock(&ubi->ltree_lock);
-
- up_write(&le->mutex);
- if (free)
kfree(le);
+ }
+ spin_unlock(&ubi->ltree_lock);
}
/**