Zhihao Cheng d005f8c658 ubi: check kthread_should_stop() after the setting of task state ... A detach hung is possible when a race occurs between the detach process and the ubi background thread. The following sequences outline the race: ubi thread: if (list_empty(&ubi->works)... ubi detach: set_bit(KTHREAD_SHOULD_STOP, &kthread->flags) => by kthread_stop() wake_up_process() => ubi thread is still running, so 0 is returned ubi thread: set_current_state(TASK_INTERRUPTIBLE) schedule() => ubi thread will never be scheduled again ubi detach: wait_for_completion() => hung task! To fix that, we need to check kthread_should_stop() after we set the task state, so the ubi thread will either see the stop bit and exit or the task state is reset to runnable such that it isn't scheduled out indefinitely. Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com> Cc: <stable@vger.kernel.org> Fixes: 801c135ce7 ("UBI: Unsorted Block Images") Reported-by: syzbot+853639d0cb16c31c7a14@syzkaller.appspotmail.com Signed-off-by: Richard Weinberger <richard@nod.at>		2020-09-17 22:55:59 +02:00
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attach.c	mtd: Convert fallthrough comments into statements	2020-03-30 10:14:54 +02:00
block.c
build.c	ubi: Relax the 'no MLC' rule and allow MLCs operating in SLC mode	2020-05-11 09:51:42 +02:00
cdev.c
debug.c	ubi: Fix seq_file usage in detailed_erase_block_info debugfs file	2020-05-17 23:38:21 +02:00
debug.h
eba.c	treewide: Remove uninitialized_var() usage	2020-07-16 12:35:15 -07:00
fastmap-wl.c	ubi: fastmap: Free fastmap next anchor peb during detach	2020-08-02 23:56:13 +02:00
fastmap.c	ubi: Select fastmap anchor PEBs considering wear level rules	2020-06-02 22:53:05 +02:00
gluebi.c
io.c	mm: remove the pgprot argument to __vmalloc	2020-06-02 10:59:11 -07:00
kapi.c
Kconfig
Makefile
misc.c
ubi-media.h	ubi: ubi-media.h: Replace zero-length array with flexible-array member	2020-03-30 23:02:37 +02:00
ubi.h	This pull request contains a single change for UBI:	2020-06-10 13:24:40 -07:00
upd.c
vmt.c
vtbl.c	ubi: Free the normal volumes in error paths of ubi_attach_mtd_dev()	2020-01-16 23:35:59 +01:00
wl.c	ubi: check kthread_should_stop() after the setting of task state	2020-09-17 22:55:59 +02:00
wl.h