| Message ID | 1494506343-28572-2-git-send-email-ulf.hansson@linaro.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 11/05/17 15:39, Ulf Hansson wrote: > In a step to simplify the use of the lock, mmc_claim|release_host(), let's > change the SDIO IRQ thread to move away from using the abort-able claim > host method. > > In the SDIO IRQ thread case, we can instead check the numbers of SDIO IRQs > that are currently claimed via host->sdio_irqs, as this field is protected > from updates unless the host is claimed. When host->sdio_irqs has become > zero, it means the SDIO func driver(s) has released the SDIO IRQ, then we > can bail out and stop running the SDIO IRQ thread. Does that work? It looks a like kthread_stop() will wait on the thread, which is waiting to claim the host, which is claimed by the caller of sdio_card_irq_put() which called kthread_stop() i.e. deadlock. > > Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org> > --- > drivers/mmc/core/sdio_irq.c | 10 ++++++---- > include/linux/mmc/host.h | 1 - > 2 files changed, 6 insertions(+), 5 deletions(-) > > diff --git a/drivers/mmc/core/sdio_irq.c b/drivers/mmc/core/sdio_irq.c > index 6d4b720..95f7a09 100644 > --- a/drivers/mmc/core/sdio_irq.c > +++ b/drivers/mmc/core/sdio_irq.c > @@ -137,9 +137,13 @@ static int sdio_irq_thread(void *_host) > * holding of the host lock does not cover too much work > * that doesn't require that lock to be held. > */ > - ret = __mmc_claim_host(host, &host->sdio_irq_thread_abort); > - if (ret) > + mmc_claim_host(host); > + if (!host->sdio_irqs) { > + ret = 1; > + mmc_release_host(host); > break; > + } > + > ret = process_sdio_pending_irqs(host); > host->sdio_irq_pending = false; > mmc_release_host(host); > @@ -195,7 +199,6 @@ static int sdio_card_irq_get(struct mmc_card *card) > > if (!host->sdio_irqs++) { > if (!(host->caps2 & MMC_CAP2_SDIO_IRQ_NOTHREAD)) { > - atomic_set(&host->sdio_irq_thread_abort, 0); > host->sdio_irq_thread = > kthread_run(sdio_irq_thread, host, > "ksdioirqd/%s", mmc_hostname(host)); > @@ -223,7 +226,6 @@ static int sdio_card_irq_put(struct mmc_card *card) > > if (!--host->sdio_irqs) { > if (!(host->caps2 & MMC_CAP2_SDIO_IRQ_NOTHREAD)) { > - atomic_set(&host->sdio_irq_thread_abort, 1); > kthread_stop(host->sdio_irq_thread); > } else if (host->caps & MMC_CAP_SDIO_IRQ) { > host->ops->enable_sdio_irq(host, 0); > diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h > index 21385ac..8a4131f 100644 > --- a/include/linux/mmc/host.h > +++ b/include/linux/mmc/host.h > @@ -359,7 +359,6 @@ struct mmc_host { > unsigned int sdio_irqs; > struct task_struct *sdio_irq_thread; > bool sdio_irq_pending; > - atomic_t sdio_irq_thread_abort; > > mmc_pm_flag_t pm_flags; /* requested pm features */ > >
On 12 May 2017 at 09:42, Adrian Hunter <adrian.hunter@intel.com> wrote: > On 11/05/17 15:39, Ulf Hansson wrote: >> In a step to simplify the use of the lock, mmc_claim|release_host(), let's >> change the SDIO IRQ thread to move away from using the abort-able claim >> host method. >> >> In the SDIO IRQ thread case, we can instead check the numbers of SDIO IRQs >> that are currently claimed via host->sdio_irqs, as this field is protected >> from updates unless the host is claimed. When host->sdio_irqs has become >> zero, it means the SDIO func driver(s) has released the SDIO IRQ, then we >> can bail out and stop running the SDIO IRQ thread. > > Does that work? It looks a like kthread_stop() will wait on the thread, > which is waiting to claim the host, which is claimed by the caller of > sdio_card_irq_put() which called kthread_stop() i.e. deadlock. Adrian, you are right and thanks for your analyze! Maybe it's better that I first continue with my other series, converting the kthread to a work/work-queue. As that makes it easier to move away from using the abort-able claim host API. Kind regards Uffe > >> >> Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org> >> --- >> drivers/mmc/core/sdio_irq.c | 10 ++++++---- >> include/linux/mmc/host.h | 1 - >> 2 files changed, 6 insertions(+), 5 deletions(-) >> >> diff --git a/drivers/mmc/core/sdio_irq.c b/drivers/mmc/core/sdio_irq.c >> index 6d4b720..95f7a09 100644 >> --- a/drivers/mmc/core/sdio_irq.c >> +++ b/drivers/mmc/core/sdio_irq.c >> @@ -137,9 +137,13 @@ static int sdio_irq_thread(void *_host) >> * holding of the host lock does not cover too much work >> * that doesn't require that lock to be held. >> */ >> - ret = __mmc_claim_host(host, &host->sdio_irq_thread_abort); >> - if (ret) >> + mmc_claim_host(host); >> + if (!host->sdio_irqs) { >> + ret = 1; >> + mmc_release_host(host); >> break; >> + } >> + >> ret = process_sdio_pending_irqs(host); >> host->sdio_irq_pending = false; >> mmc_release_host(host); >> @@ -195,7 +199,6 @@ static int sdio_card_irq_get(struct mmc_card *card) >> >> if (!host->sdio_irqs++) { >> if (!(host->caps2 & MMC_CAP2_SDIO_IRQ_NOTHREAD)) { >> - atomic_set(&host->sdio_irq_thread_abort, 0); >> host->sdio_irq_thread = >> kthread_run(sdio_irq_thread, host, >> "ksdioirqd/%s", mmc_hostname(host)); >> @@ -223,7 +226,6 @@ static int sdio_card_irq_put(struct mmc_card *card) >> >> if (!--host->sdio_irqs) { >> if (!(host->caps2 & MMC_CAP2_SDIO_IRQ_NOTHREAD)) { >> - atomic_set(&host->sdio_irq_thread_abort, 1); >> kthread_stop(host->sdio_irq_thread); >> } else if (host->caps & MMC_CAP_SDIO_IRQ) { >> host->ops->enable_sdio_irq(host, 0); >> diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h >> index 21385ac..8a4131f 100644 >> --- a/include/linux/mmc/host.h >> +++ b/include/linux/mmc/host.h >> @@ -359,7 +359,6 @@ struct mmc_host { >> unsigned int sdio_irqs; >> struct task_struct *sdio_irq_thread; >> bool sdio_irq_pending; >> - atomic_t sdio_irq_thread_abort; >> >> mmc_pm_flag_t pm_flags; /* requested pm features */ >> >> >
diff --git a/drivers/mmc/core/sdio_irq.c b/drivers/mmc/core/sdio_irq.c index 6d4b720..95f7a09 100644 --- a/drivers/mmc/core/sdio_irq.c +++ b/drivers/mmc/core/sdio_irq.c @@ -137,9 +137,13 @@ static int sdio_irq_thread(void *_host) * holding of the host lock does not cover too much work * that doesn't require that lock to be held. */ - ret = __mmc_claim_host(host, &host->sdio_irq_thread_abort); - if (ret) + mmc_claim_host(host); + if (!host->sdio_irqs) { + ret = 1; + mmc_release_host(host); break; + } + ret = process_sdio_pending_irqs(host); host->sdio_irq_pending = false; mmc_release_host(host); @@ -195,7 +199,6 @@ static int sdio_card_irq_get(struct mmc_card *card) if (!host->sdio_irqs++) { if (!(host->caps2 & MMC_CAP2_SDIO_IRQ_NOTHREAD)) { - atomic_set(&host->sdio_irq_thread_abort, 0); host->sdio_irq_thread = kthread_run(sdio_irq_thread, host, "ksdioirqd/%s", mmc_hostname(host)); @@ -223,7 +226,6 @@ static int sdio_card_irq_put(struct mmc_card *card) if (!--host->sdio_irqs) { if (!(host->caps2 & MMC_CAP2_SDIO_IRQ_NOTHREAD)) { - atomic_set(&host->sdio_irq_thread_abort, 1); kthread_stop(host->sdio_irq_thread); } else if (host->caps & MMC_CAP_SDIO_IRQ) { host->ops->enable_sdio_irq(host, 0); diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h index 21385ac..8a4131f 100644 --- a/include/linux/mmc/host.h +++ b/include/linux/mmc/host.h @@ -359,7 +359,6 @@ struct mmc_host { unsigned int sdio_irqs; struct task_struct *sdio_irq_thread; bool sdio_irq_pending; - atomic_t sdio_irq_thread_abort; mmc_pm_flag_t pm_flags; /* requested pm features */
In a step to simplify the use of the lock, mmc_claim|release_host(), let's change the SDIO IRQ thread to move away from using the abort-able claim host method. In the SDIO IRQ thread case, we can instead check the numbers of SDIO IRQs that are currently claimed via host->sdio_irqs, as this field is protected from updates unless the host is claimed. When host->sdio_irqs has become zero, it means the SDIO func driver(s) has released the SDIO IRQ, then we can bail out and stop running the SDIO IRQ thread. Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org> --- drivers/mmc/core/sdio_irq.c | 10 ++++++---- include/linux/mmc/host.h | 1 - 2 files changed, 6 insertions(+), 5 deletions(-)