mtd: nand: fix shutdown/reboot for multi-chip systems

[Linux-MTD Mailing List]

Gitweb:     http://git.infradead.org/?p=mtd-2.6.git;a=commit;h=9ca641b0f02a3a1eedbc8c296e695326da9bbaf9
Commit:     9ca641b0f02a3a1eedbc8c296e695326da9bbaf9
Parent:     96dd922c198286681fbbc15100e196e0f629e2fb
Author:     Brian Norris <computersforpeace at gmail.com>
AuthorDate: Mon Nov 9 16:37:28 2015 -0800
Committer:  Brian Norris <computersforpeace at gmail.com>
CommitDate: Mon Nov 16 10:51:39 2015 -0800

    mtd: nand: fix shutdown/reboot for multi-chip systems
    
    If multiple NAND chips are registered to the same controller, then when
    rebooting the system, the first one will grab the controller lock, while
    the second will wait forever for the first one to release it. i.e., a
    classic deadlock.
    
    This problem was solved for a similar case (suspend/resume) back in
    commit 6b0d9a841249 ("mtd: nand: fix multi-chip suspend problem"), and
    the shutdown state really isn't much different for us, so rather than
    adding a new special case to nand_get_device(), we can just overload the
    FL_PM_SUSPENDED state.
    
    Now, multiple chips can "get" the same controller lock (preventing
    further I/O), while we still allow other chips to pass through
    nand_shutdown().
    
    Original report:
    http://thread.gmane.org/gmane.linux.drivers.mtd/59726
    http://lists.infradead.org/pipermail/linux-mtd/2015-July/059992.html
    
    Fixes: 72ea403669c7 ("mtd: nand: added nand_shutdown")
    Reported-by: Andrew E. Mileski <andrewm at isoar.ca>
    Signed-off-by: Brian Norris <computersforpeace at gmail.com>
    Cc: Scott Branden <sbranden at broadcom.com>
    Cc: Andrew E. Mileski <andrewm at isoar.ca>
    Acked-by: Scott Branden <sbranden at broadcom.com>
    Reviewed-by: Boris Brezillon <boris.brezillon at free-electrons.com>
---
 drivers/mtd/nand/nand_base.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
index cc74142..ece544e 100644
--- a/drivers/mtd/nand/nand_base.c
+++ b/drivers/mtd/nand/nand_base.c
@@ -3110,7 +3110,7 @@ static void nand_resume(struct mtd_info *mtd)
  */
 static void nand_shutdown(struct mtd_info *mtd)
 {
-	nand_get_device(mtd, FL_SHUTDOWN);
+	nand_get_device(mtd, FL_PM_SUSPENDED);
 }
 
 /* Set default functions */