Commit 6e7d8016 authored May 16, 2018 by Richard Weinberger

ubi: fastmap: Cancel work upon detach



Ben Hutchings pointed out that 29b7a6fa ("ubi: fastmap: Don't flush
fastmap work on detach") does not really fix the problem, it just
reduces the risk to hit the race window where fastmap work races against
free()'ing ubi->volumes[].

The correct approach is making sure that no more fastmap work is in
progress before we free ubi data structures.
So we cancel fastmap work right after the ubi background thread is
stopped.
By setting ubi->thread_enabled to zero we make sure that no further work
tries to wake the thread.

Fixes: 29b7a6fa ("ubi: fastmap: Don't flush fastmap work on detach")
Fixes: 74cdaf24 ("UBI: Fastmap: Fix memory leaks while closing the WL sub-system")
Cc: stable@vger.kernel.org
Cc: Ben Hutchings <ben.hutchings@codethink.co.uk>
Cc: Martin Townsend <mtownsend1973@gmail.com>

Signed-off-by: Richard Weinberger <richard@nod.at>

parent e1db654d

drivers/mtd/ubi/build.c

+3 −0

Original line number	Diff line number	Diff line
		@@ -1091,6 +1091,9 @@ int ubi_detach_mtd_dev(int ubi_num, int anyway)
		if (ubi->bgt_thread)
		kthread_stop(ubi->bgt_thread);

		#ifdef CONFIG_MTD_UBI_FASTMAP
		cancel_work_sync(&ubi->fm_work);
		#endif
		ubi_debugfs_exit_dev(ubi);
		uif_close(ubi);

drivers/mtd/ubi/wl.c

+1 −3

Original line number	Diff line number	Diff line
		@@ -1505,6 +1505,7 @@ int ubi_thread(void *u)
		}

		dbg_wl("background thread \"%s\" is killed", ubi->bgt_name);
		ubi->thread_enabled = 0;
		return 0;
		}

		@@ -1514,9 +1515,6 @@ int ubi_thread(void *u)
		*/
		static void shutdown_work(struct ubi_device *ubi)
		{
		#ifdef CONFIG_MTD_UBI_FASTMAP
		flush_work(&ubi->fm_work);
		#endif
		while (!list_empty(&ubi->works)) {
		struct ubi_work *wrk;

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