• Alexandre Bounine's avatar
    rapidio/tsi721: fix tasklet termination in dma channel release · 04379dff
    Alexandre Bounine authored
    This patch is a modification of the patch originally proposed by
    Xiaotian Feng <xtfeng@gmail.com>: https://lkml.org/lkml/2012/11/5/413
    This new version disables DMA channel interrupts and ensures that the
    tasklet wil not be scheduled again before calling tasklet_kill().
    
    Unfortunately the updated patch was not released at that time due to
    planned rework of Tsi721 mport driver to use threaded interrupts (which
    has yet to happen).  Recently the issue was reported again:
    https://lkml.org/lkml/2014/2/19/762.
    
    Description from the original Xiaotian's patch:
    
     "Some drivers use tasklet_disable in device remove/release process,
      tasklet_disable will inc tasklet->count and return.  If the tasklet is
      not handled yet under some softirq pressure, the tasklet will be
      placed on the tasklet_vec, never have a chance to be excuted.  This
      might lead to a heavy loaded ksoftirqd, wakeup with pending_softirq,
      but tasklet is disabled.  tasklet_kill should be used in this case."
    
    This patch is applicable to kernel versions starting from v3.5.
    Signed-off-by: default avatarAlexandre Bounine <alexandre.bounine@idt.com>
    Cc: Matt Porter <mporter@kernel.crashing.org>
    Cc: Xiaotian Feng <xtfeng@gmail.com>
    Reviewed-by: default avatarThomas Gleixner <tglx@linutronix.de>
    Cc: Mike Galbraith <bitbucket@online.de>
    Cc: <stable@vger.kernel.org>	[3.5+]
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    04379dff
tsi721_dma.c 22.2 KB