Hi, On Wed, Jan 04 2012, Guennadi Liakhovetski wrote: > Performing MMC block IO with simultaneous STR can lead to a deadlock: the > mmc_pm_notify() function claims the host and then calls bus .remove() > method, which lands in mmc_blk_remove(), which calls mmc_blk_remove_req() > then it goes to -> mmc_cleanup_queue() -> kthread_stop(), which waits for > the mmc-block thread to stop. If the mmc-block thread at that time is > processing block requests, it will also try to claim the host in > mmc_blk_issue_rq() and block there. This patch fixes the problem by > calling .remove() before claiming the host. > > Signed-off-by: Guennadi Liakhovetski <[email protected]> > --- > drivers/mmc/core/core.c | 4 ++-- > 1 files changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c > index a2aa860..a68f085 100644 > --- a/drivers/mmc/core/core.c > +++ b/drivers/mmc/core/core.c > @@ -2476,11 +2476,11 @@ int mmc_pm_notify(struct notifier_block *notify_block, > if (!host->bus_ops || host->bus_ops->suspend) > break; > > - mmc_claim_host(host); > - > + /* On 2 occasions above bus_ops->remove() is called unlocked */ > if (host->bus_ops->remove) > host->bus_ops->remove(host); > > + mmc_claim_host(host); > mmc_detach_bus(host); > mmc_power_off(host); > mmc_release_host(host);
Thanks. The commit message explanation is very good, but the comment is a bit cryptic. Shall we make it longer? I think even just: /* Calling bus_ops->remove() with a claimed host can deadlock */ would be better. - Chris. -- Chris Ball <[email protected]> <http://printf.net/> One Laptop Per Child -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
