mtd: atmel_nand: fix bug driver will in a dead lock if no nand detected

[Linux-MTD Mailing List]

Gitweb:     http://git.infradead.org/?p=mtd-2.6.git;a=commit;h=a749d13acd8e079ed4c77a9456d842dc94af8f17
Commit:     a749d13acd8e079ed4c77a9456d842dc94af8f17
Parent:     97de79e02d5e85b4a147b74cc2947b8613d806f7
Author:     Josh Wu <josh.wu at atmel.com>
AuthorDate: Tue Nov 5 17:59:07 2013 +0800
Committer:  Brian Norris <computersforpeace at gmail.com>
CommitDate: Thu Nov 7 10:16:21 2013 -0800

    mtd: atmel_nand: fix bug driver will in a dead lock if no nand detected
    
    In the atmel driver probe function, the code shows like following:
      atmel_nand_probe(...) {
            ...
    
      err_nand_ioremap:
            platform_driver_unregister(&atmel_nand_nfc_driver);
            return res;
      }
    
    If no nand flash detected, the driver probe function will goto
    err_nand_ioremap label.
    Then platform_driver_unregister() will be called. It will get the
    lock of atmel_nand device since it is parent of nfc_device. The
    problem is the lock is already hold by atmel_nand_probe itself.
    So system will be in a dead lock.
    
    This patch just simply removed to platform_driver_unregister() call.
    When atmel_nand driver is quit the platform_driver_unregister() will
    be called in atmel_nand_remove().
    
    [Brian: the NAND platform probe really has no business
     registering/unregistering another driver; this fixes the deadlock, but
     we should follow up the likely racy behavior here with a better
     architecture]
    
    Signed-off-by: Josh Wu <josh.wu at atmel.com>
    Cc: <stable at vger.kernel.org> # 3.12
    Signed-off-by: Brian Norris <computersforpeace at gmail.com>
---
 drivers/mtd/nand/atmel_nand.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/drivers/mtd/nand/atmel_nand.c b/drivers/mtd/nand/atmel_nand.c
index ef9c9f5..469d4e2 100644
--- a/drivers/mtd/nand/atmel_nand.c
+++ b/drivers/mtd/nand/atmel_nand.c
@@ -2142,7 +2142,6 @@ err_no_card:
 	if (host->dma_chan)
 		dma_release_channel(host->dma_chan);
 err_nand_ioremap:
-	platform_driver_unregister(&atmel_nand_nfc_driver);
 	return res;
 }