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| author | Artem Bityutskiy <Artem.Bityutskiy@nokia.com> | 2009-05-23 13:44:09 +0300 |
|---|---|---|
| committer | Artem Bityutskiy <Artem.Bityutskiy@nokia.com> | 2009-05-26 12:47:47 +0300 |
| commit | ddbd3b61708483f73dbcc62a94d16cc7db928cba (patch) | |
| tree | 7600caa289d1517e8642d6be21d0a0cfe88c40d5 | |
| parent | 95c9c1da79e59fd10ec5da3aeba22981383f7040 (diff) | |
| download | kernel_samsung_smdk4412-ddbd3b61708483f73dbcc62a94d16cc7db928cba.zip kernel_samsung_smdk4412-ddbd3b61708483f73dbcc62a94d16cc7db928cba.tar.gz kernel_samsung_smdk4412-ddbd3b61708483f73dbcc62a94d16cc7db928cba.tar.bz2 | |
UBI: fix race condition
This patch fixes a minor problem where we may fail to wake
upe the UBI background thread. This is not fatal at all,
it may just result at sligtly worse performace for a short
period of time, just because the thread will be woken up
when real I/O on the UBI starts.
Anywey, the issue is the race condition between
'ubi_attach_mtd_dev()' and 'ubi_thread()'. If we do not
serialize them, the 'wake_up_process()' call may be done
before 'ubi_thread()' went seep, but after it checked
'ubi->thread_enabled'.
This issue was spotted by Shin Hong <hongshin@gmail.com>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
| -rw-r--r-- | drivers/mtd/ubi/build.c | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/drivers/mtd/ubi/build.c b/drivers/mtd/ubi/build.c index 2c3269e..1405b55 100644 --- a/drivers/mtd/ubi/build.c +++ b/drivers/mtd/ubi/build.c @@ -380,7 +380,7 @@ static void free_user_volumes(struct ubi_device *ubi) * @ubi: UBI device description object * * This function returns zero in case of success and a negative error code in - * case of failure. Note, this function destroys all volumes if it failes. + * case of failure. Note, this function destroys all volumes if it fails. */ static int uif_init(struct ubi_device *ubi) { @@ -871,9 +871,15 @@ int ubi_attach_mtd_dev(struct mtd_info *mtd, int ubi_num, int vid_hdr_offset) ubi->beb_rsvd_pebs); ubi_msg("max/mean erase counter: %d/%d", ubi->max_ec, ubi->mean_ec); + /* + * The below lock makes sure we do not race with 'ubi_thread()' which + * checks @ubi->thread_enabled. Otherwise we may fail to wake it up. + */ + spin_lock(&ubi->wl_lock); if (!DBG_DISABLE_BGT) ubi->thread_enabled = 1; wake_up_process(ubi->bgt_thread); + spin_unlock(&ubi->wl_lock); ubi_devices[ubi_num] = ubi; return ubi_num; |