On Mon, 2010-06-21 at 23:04 +0300, Adrian Hunter wrote: > ext Maxim Levitsky wrote: > > If you don't use CONFIG_MMC_UNSAFE_RESUME, as soon as you attempt to > > suspend, the card will be removed, therefore this patch doesn't change > > the behavior of this option. > > > > However the removal will be done by pm notifier, which runs while > > userspace is still not frozen and thus can freely use del_gendisk, > > without the risk of deadlock which would happen otherwise. > > > > > > Card detect workqueue is now freezeable, > > therefore if you do use CONFIG_MMC_UNSAFE_RESUME, > > and remove the card during suspend, the removal will be > > detected as soon as userspace is unfrozen, again at the moment > > it is safe to call del_gendisk. > > > > Tested with and without CONFIG_MMC_UNSAFE_RESUME with suspend and hibernate. > > > > Signed-off-by: Maxim Levitsky <[email protected]> > > --- > > drivers/mmc/core/core.c | 54 > > +++++++++++++++++++++++++++------------------ > > drivers/mmc/core/host.c | 6 +++++ > > include/linux/mmc/host.h | 3 ++ > > 3 files changed, 41 insertions(+), 22 deletions(-) > > > > diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c > > index 569e94d..0cba53a 100644 > > --- a/drivers/mmc/core/core.c > > +++ b/drivers/mmc/core/core.c > > @@ -1259,26 +1259,11 @@ int mmc_suspend_host(struct mmc_host *host) > > > > if (host->caps & MMC_CAP_DISABLE) > > cancel_delayed_work(&host->disable); > > - cancel_delayed_work(&host->detect); > > - mmc_flush_scheduled_work(); > > > > mmc_bus_get(host); > > if (host->bus_ops && !host->bus_dead) { > > if (host->bus_ops->suspend) > > err = host->bus_ops->suspend(host); > > - if (err == -ENOSYS || !host->bus_ops->resume) { > > - /* > > - * We simply "remove" the card in this case. > > - * It will be redetected on resume. > > - */ > > - if (host->bus_ops->remove) > > - host->bus_ops->remove(host); > > - mmc_claim_host(host); > > - mmc_detach_bus(host); > > - mmc_release_host(host); > > - host->pm_flags = 0; > > - err = 0; > > - } > > } > > mmc_bus_put(host); > > > > @@ -1310,12 +1295,6 @@ int mmc_resume_host(struct mmc_host *host) > > printk(KERN_WARNING "%s: error %d during resume " > > "(card was removed?)\n", > > mmc_hostname(host), err); > > - if (host->bus_ops->remove) > > - host->bus_ops->remove(host); > > - mmc_claim_host(host); > > - mmc_detach_bus(host); > > - mmc_release_host(host); > > - /* no need to bother upper layers */ > > err = 0; > > } > > } > > @@ -1330,6 +1309,37 @@ int mmc_resume_host(struct mmc_host *host) > > return err; > > } > > > > +/* Do the card removal on suspend if card is assumed removeable > > + * Do that in pm notifier while userspace isn't yet frozen, so we will be > > able > > + to sync the card. > > +*/ > > +int mmc_pm_notify(struct notifier_block *notify_block, > > + unsigned long mode, void *unused) > > +{ > > + struct mmc_host *host = container_of( > > + notify_block, struct mmc_host, pm_notify); > > + > > + > > + switch (mode) { > > + case PM_HIBERNATION_PREPARE: > > + case PM_SUSPEND_PREPARE: > > + > > + if (!host->bus_ops || host->bus_ops->suspend) > > + break; > > + > > + if (host->bus_ops->remove) > > + host->bus_ops->remove(host); > > + mmc_claim_host(host); > > + mmc_detach_bus(host); > > + mmc_release_host(host); > > + host->pm_flags = 0; > > + break; > > Is it possible that you receive PM_SUSPEND_PREPARE > but there is no suspend and therefore no resume > and therefore the card is removed but not detected > again? This is very good point. The solution is to kick mmc detection thread from this notifier. on resume. I update the patch.
> > Is it possible that you are racing with kmmcd and the > card is added after you receive PM_SUSPEND_PREPARE but > before kmmcd is frozen? This is unlikely but valid race. I afraid I don't know nice way to solve it right now. I can add some ad-hoc variable to tell interrupt handler not to kick the detection workqueue after suspend notifier was called. I wish there was a generic freeze_workqueue function. Best regards, Maxim Levitsky -- 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
