Hi, Rafael > From: Rafael J. Wysocki [mailto:rjw@xxxxxxxxxxxxx] > Sent: Wednesday, November 12, 2014 9:17 AM > > On Monday, November 03, 2014 01:16:37 PM Lv Zheng wrote: > > There is wait code in the QR_SC command processing, which makes it not > > suitable to be put into a work queue item (see bug 82611). And there is > > case that the SCI_EVT cannot trigger GPE, though all commands have polling > > mode implemented, the event cannot be polled (see bug 77431). > > > > So if the QR_SC command can be put into a seperate IRQ thread, then the > > work queue will not be blocked by the QR_SC command processing and we can > > also trigger polling using the thread. Using IRQ thread also allows us to > > change the EC GPE handler into the threaded IRQ model when possible. > > > > This patch thus adds the IRQ polling thread for SCI_EVT polling and removes > > QR_SC processing work item. > > > > The reasons why we do not put a loop in the event poller to poll event > > until the returned query value is 0: > > Some platforms return non 0 query value even when SCI_EVT=0, if we put a > > loop in the poller, our command flush mechanism could never execute to > > an end thus the system suspending process could be blocked. One SCI_EVT > > triggering one QR_EC is current logic and has been proven to be working > > for so long time. > > > > The reasons why it is not implemented directly using threaded IRQ are: > > 1. ACPICA doesn't support threaded IRQ as not all of the OSPMs support > > threaded IRQ while GPE handler registerations are done through ACPICA. > > 2. The IRQ processing code need to be identical for both the IRQ handler > > and the thread callback, while currently, though the command GPE > > handling is ready for both IRQ and polling mode, only the event GPE is > > is polled in the event polling thread and the command is polled in the > > user threads. > > So we use a standalone kernel thread, if the above situations are changed > > in the future, we can easily convert the code into the threaded IRQ style. > > > > The old EC_FLAGS_QUERY_PENDING is converted to EC_FLAGS_EVENT_ENABLED in > > this patch, so that its naming is consistent with EC_FLAGS_EVENT_PENDING. > > The original flag doesn't co-work with SCI_EVT well, this patch refines > > its usage by enforcing a event polling wakeup indication as: > > EC_FLAGS_EVENT_ENABLED && EC_FLAGS_EVENT_PENDING > > So unless the both of the flags are set, the threaded event poller will > > not be woken up. > > > > This patch invokes acpi_ec_submit_request() after having detected SCI_EVT > > and invokes acpi_ec_complete_request() before having the QR_EC command > > processed. This is useful for implementing GPE storm prevention for > > malicous "level triggered" SCI_EVT. But the storm prevention is not > > implemented in this patch. > > > > Since the acpi_ec_submit_request() invoked after detecting the SCI_EVT is > > paired with acpi_ec_complete_request() invoked after completing QR_EC > > command, acpi_ec_submit_flushable_request() then need to be modified to > > allow QR_EC command to be submitted during this period to revert the > > increased reference count. This period can be determined by the event > > polling indication: > > EC_FLAGS_EVENT_ENABLED && EC_FLAGS_EVENT_PENDING > > Without enhancing this check in acpi_ec_submit_flushable_request(), QR_EC > > command will not be executed to decrease the reference count added after > > detecting the SCI_EVT, thus the system suspending will be blocked because > > the reference count equals to 2. Such check is common for flushing code. > > > > Reference: https://bugzilla.kernel.org/show_bug.cgi?id=82611 > > Reference: https://bugzilla.kernel.org/show_bug.cgi?id=77431 > > Signed-off-by: Lv Zheng <lv.zheng@xxxxxxxxx> > > Tested-by: Ortwin Glück <odi@xxxxxx> > > --- > > drivers/acpi/ec.c | 194 ++++++++++++++++++++++++++++++++++------------- > > drivers/acpi/internal.h | 1 + > > 2 files changed, 144 insertions(+), 51 deletions(-) > > > > diff --git a/drivers/acpi/ec.c b/drivers/acpi/ec.c > > index a76794a..7089081 100644 > > --- a/drivers/acpi/ec.c > > +++ b/drivers/acpi/ec.c > > @@ -44,6 +44,7 @@ > > #include <linux/slab.h> > > #include <linux/acpi.h> > > #include <linux/dmi.h> > > +#include <linux/kthread.h> > > #include <asm/io.h> > > > > #include "internal.h" > > @@ -75,7 +76,8 @@ enum ec_command { > > * when trying to clear the EC */ > > > > enum { > > - EC_FLAGS_QUERY_PENDING, /* Query is pending */ > > + EC_FLAGS_EVENT_ENABLED, /* Event is enabled */ > > + EC_FLAGS_EVENT_PENDING, /* Event is pending */ > > EC_FLAGS_GPE_STORM, /* GPE storm detected */ > > EC_FLAGS_HANDLERS_INSTALLED, /* Handlers for GPE and > > * OpReg are installed */ > > @@ -124,6 +126,7 @@ struct transaction { > > static struct acpi_ec_query_handler * > > acpi_ec_get_query_handler(struct acpi_ec_query_handler *handler); > > static void acpi_ec_put_query_handler(struct acpi_ec_query_handler *handler); > > +static int acpi_ec_sync_query(struct acpi_ec *ec, u8 *data); > > > > struct acpi_ec *boot_ec, *first_ec; > > EXPORT_SYMBOL(first_ec); > > @@ -149,6 +152,12 @@ static bool acpi_ec_flushed(struct acpi_ec *ec) > > return ec->reference_count == 1; > > } > > > > +static bool acpi_ec_has_pending_event(struct acpi_ec *ec) > > +{ > > + return test_bit(EC_FLAGS_EVENT_ENABLED, &ec->flags) && > > + test_bit(EC_FLAGS_EVENT_PENDING, &ec->flags); > > +} > > + > > /* -------------------------------------------------------------------------- > > * GPE Enhancement > > * -------------------------------------------------------------------------- */ > > @@ -177,20 +186,93 @@ static void acpi_ec_complete_request(struct acpi_ec *ec) > > * the flush operation is not in > > * progress > > * @ec: the EC device > > + * @check_event: check whether event is pending > > * > > * This function must be used before taking a new action that should hold > > * the reference count. If this function returns false, then the action > > * must be discarded or it will prevent the flush operation from being > > * completed. > > + * > > + * During flushing, QR_EC command need to pass this check when there is a > > + * pending event, so that the reference count held for the pending event > > + * can be decreased by the completion of the QR_EC command. > > */ > > -static bool acpi_ec_submit_flushable_request(struct acpi_ec *ec) > > +static bool acpi_ec_submit_flushable_request(struct acpi_ec *ec, > > + bool check_event) > > { > > - if (!acpi_ec_started(ec)) > > - return false; > > + if (!acpi_ec_started(ec)) { > > + if (!check_event || !acpi_ec_has_pending_event(ec)) > > + return false; > > + } > > acpi_ec_submit_request(ec); > > return true; > > } > > > > +static void acpi_ec_enable_event(struct acpi_ec *ec) > > +{ > > + unsigned long flags; > > + > > + spin_lock_irqsave(&ec->lock, flags); > > + /* Hold reference for pending event */ > > + if (!acpi_ec_submit_flushable_request(ec, false)) { > > + spin_unlock_irqrestore(&ec->lock, flags); > > + return; > > + } > > + set_bit(EC_FLAGS_EVENT_ENABLED, &ec->flags); > > + if (test_bit(EC_FLAGS_EVENT_PENDING, &ec->flags)) { > > + pr_debug("***** Event pending *****\n"); > > + wake_up_process(ec->thread); > > + spin_unlock_irqrestore(&ec->lock, flags); > > + return; > > + } > > + acpi_ec_complete_request(ec); > > + spin_unlock_irqrestore(&ec->lock, flags); > > +} > > + > > +static void __acpi_ec_set_event(struct acpi_ec *ec) > > +{ > > + /* Hold reference for pending event */ > > + if (!acpi_ec_submit_flushable_request(ec, false)) > > + return; > > + if (!test_and_set_bit(EC_FLAGS_EVENT_PENDING, &ec->flags)) { > > + pr_debug("***** Event pending *****\n"); > > + if (test_bit(EC_FLAGS_EVENT_ENABLED, &ec->flags)) { > > + wake_up_process(ec->thread); > > + return; > > + } > > + } > > + acpi_ec_complete_request(ec); > > +} > > + > > +static void __acpi_ec_complete_event(struct acpi_ec *ec) > > +{ > > + if (test_and_clear_bit(EC_FLAGS_EVENT_PENDING, &ec->flags)) { > > + /* Unhold reference for pending event */ > > + acpi_ec_complete_request(ec); > > + pr_debug("***** Event running *****\n"); > > + } > > +} > > + > > +int acpi_ec_wait_for_event(struct acpi_ec *ec) > > +{ > > + unsigned long flags; > > + > > + set_current_state(TASK_INTERRUPTIBLE); > > + while (!kthread_should_stop()) { > > + spin_lock_irqsave(&ec->lock, flags); > > + if (acpi_ec_has_pending_event(ec)) { > > + spin_unlock_irqrestore(&ec->lock, flags); > > + __set_current_state(TASK_RUNNING); > > + return 0; > > + } > > + spin_unlock_irqrestore(&ec->lock, flags); > > + schedule(); > > + set_current_state(TASK_INTERRUPTIBLE); > > + } > > + __set_current_state(TASK_RUNNING); > > + return -1; > > +} > > + > > /* -------------------------------------------------------------------------- > > * Transaction Management > > * -------------------------------------------------------------------------- */ > > @@ -298,7 +380,7 @@ static bool advance_transaction(struct acpi_ec *ec) > > t->flags |= ACPI_EC_COMMAND_COMPLETE; > > wakeup = true; > > } > > - return wakeup; > > + goto out; > > } else { > > if (EC_FLAGS_QUERY_HANDSHAKE && > > !(status & ACPI_EC_FLAG_SCI) && > > @@ -312,9 +394,11 @@ static bool advance_transaction(struct acpi_ec *ec) > > } else if ((status & ACPI_EC_FLAG_IBF) == 0) { > > acpi_ec_write_cmd(ec, t->command); > > t->flags |= ACPI_EC_COMMAND_POLL; > > + if (t->command == ACPI_EC_COMMAND_QUERY) > > + __acpi_ec_complete_event(ec); > > } else > > goto err; > > - return wakeup; > > + goto out; > > } > > err: > > /* > > @@ -325,6 +409,10 @@ err: > > if (in_interrupt() && t) > > ++t->irq_count; > > } > > +out: > > + if (status & ACPI_EC_FLAG_SCI && > > + (!t || t->flags & ACPI_EC_COMMAND_COMPLETE)) > > + __acpi_ec_set_event(ec); > > return wakeup; > > } > > > > @@ -335,17 +423,6 @@ static void start_transaction(struct acpi_ec *ec) > > (void)advance_transaction(ec); > > } > > > > -static int acpi_ec_sync_query(struct acpi_ec *ec, u8 *data); > > - > > -static int ec_check_sci_sync(struct acpi_ec *ec, u8 state) > > -{ > > - if (state & ACPI_EC_FLAG_SCI) { > > - if (!test_and_set_bit(EC_FLAGS_QUERY_PENDING, &ec->flags)) > > - return acpi_ec_sync_query(ec, NULL); > > - } > > - return 0; > > -} > > - > > static int ec_poll(struct acpi_ec *ec) > > { > > unsigned long flags; > > @@ -384,12 +461,13 @@ static int acpi_ec_transaction_unlocked(struct acpi_ec *ec, > > unsigned long tmp; > > int ret = 0; > > > > + bool is_query = !!(t->command == ACPI_EC_COMMAND_QUERY); > > if (EC_FLAGS_MSI) > > udelay(ACPI_EC_MSI_UDELAY); > > /* start transaction */ > > spin_lock_irqsave(&ec->lock, tmp); > > /* Enable GPE for command processing (IBF=0/OBF=1) */ > > - if (!acpi_ec_submit_flushable_request(ec)) { > > + if (!acpi_ec_submit_flushable_request(ec, is_query)) { > > ret = -EINVAL; > > goto unlock; > > } > > @@ -398,10 +476,6 @@ static int acpi_ec_transaction_unlocked(struct acpi_ec *ec, > > pr_debug("***** Command(%s) started *****\n", > > acpi_ec_cmd_string(t->command)); > > start_transaction(ec); > > - if (ec->curr->command == ACPI_EC_COMMAND_QUERY) { > > - clear_bit(EC_FLAGS_QUERY_PENDING, &ec->flags); > > - pr_debug("***** Event stopped *****\n"); > > - } > > spin_unlock_irqrestore(&ec->lock, tmp); > > ret = ec_poll(ec); > > spin_lock_irqsave(&ec->lock, tmp); > > @@ -440,8 +514,6 @@ static int acpi_ec_transaction(struct acpi_ec *ec, struct transaction *t) > > > > status = acpi_ec_transaction_unlocked(ec, t); > > > > - /* check if we received SCI during transaction */ > > - ec_check_sci_sync(ec, acpi_ec_read_status(ec)); > > if (test_bit(EC_FLAGS_GPE_STORM, &ec->flags)) { > > msleep(1); > > /* It is safe to enable the GPE outside of the transaction. */ > > @@ -792,29 +864,6 @@ static int acpi_ec_sync_query(struct acpi_ec *ec, u8 *data) > > return 0; > > } > > > > -static void acpi_ec_gpe_query(void *ec_cxt) > > -{ > > - struct acpi_ec *ec = ec_cxt; > > - > > - if (!ec) > > - return; > > - mutex_lock(&ec->mutex); > > - acpi_ec_sync_query(ec, NULL); > > - mutex_unlock(&ec->mutex); > > -} > > - > > -static int ec_check_sci(struct acpi_ec *ec, u8 state) > > -{ > > - if (state & ACPI_EC_FLAG_SCI) { > > - if (!test_and_set_bit(EC_FLAGS_QUERY_PENDING, &ec->flags)) { > > - pr_debug("***** Event started *****\n"); > > - return acpi_os_execute(OSL_NOTIFY_HANDLER, > > - acpi_ec_gpe_query, ec); > > - } > > - } > > - return 0; > > -} > > - > > static u32 acpi_ec_gpe_handler(acpi_handle gpe_device, > > u32 gpe_number, void *data) > > { > > @@ -825,10 +874,46 @@ static u32 acpi_ec_gpe_handler(acpi_handle gpe_device, > > if (advance_transaction(ec)) > > wake_up(&ec->wait); > > spin_unlock_irqrestore(&ec->lock, flags); > > - ec_check_sci(ec, acpi_ec_read_status(ec)); > > return ACPI_INTERRUPT_HANDLED | ACPI_REENABLE_GPE; > > } > > > > +static int acpi_ec_event_poller(void *context) > > +{ > > + struct acpi_ec *ec = context; > > + > > + while (!acpi_ec_wait_for_event(ec)) { > > + pr_debug("***** Event poller started *****\n"); > > + mutex_lock(&ec->mutex); > > + (void)acpi_ec_sync_query(ec, NULL); > > + mutex_unlock(&ec->mutex); > > + pr_debug("***** Event poller stopped *****\n"); > > + } > > + return 0; > > +} > > + > > +static int ec_create_event_poller(struct acpi_ec *ec) > > +{ > > + struct task_struct *t; > > + > > + t = kthread_run(acpi_ec_event_poller, ec, "ec/gpe-%lu", ec->gpe); > > Does it have to be a kernel thread? > > What about using a workqueue instead? Actually I just want to use threaded IRQ here in response to Andi Kleen's comment. If acpi_irq is registered as threaded IRQ, then acpi_ec_event_poller() will be the callback from it. Since ACPICA is not ready for threaded IRQ currently, we cannot proceed at this point. So I copied the threaded IRQ code from kernel/irq/manage.c here to prepare threaded IRQ logics. Using a separate work queue, we didn't decrease the kernel thread count. And the code written for the work item cannot be derived when things are switched to the threaded IRQ. So I used kthread here. Thanks and best regards -Lv > > > + if (IS_ERR(t)) { > > + pr_err("failed to create event poller %lu\n", ec->gpe); > > + return PTR_ERR(t); > > + } > > + get_task_struct(t); > > + ec->thread = t; > > + return 0; > > +} > > + > > +static void ec_delete_event_poller(struct acpi_ec *ec) > > +{ > > + struct task_struct *t = ec->thread; > > + > > + ec->thread = NULL; > > + kthread_stop(t); > > + put_task_struct(t); > > +} > > + > > /* -------------------------------------------------------------------------- > > * Address Space Management > > * -------------------------------------------------------------------------- */ > > @@ -884,7 +969,6 @@ static struct acpi_ec *make_acpi_ec(void) > > > > if (!ec) > > return NULL; > > - ec->flags = 1 << EC_FLAGS_QUERY_PENDING; > > mutex_init(&ec->mutex); > > init_waitqueue_head(&ec->wait); > > INIT_LIST_HEAD(&ec->list); > > @@ -940,15 +1024,21 @@ ec_parse_device(acpi_handle handle, u32 Level, void *context, void **retval) > > > > static int ec_install_handlers(struct acpi_ec *ec) > > { > > + int ret; > > acpi_status status; > > > > if (test_bit(EC_FLAGS_HANDLERS_INSTALLED, &ec->flags)) > > return 0; > > + ret = ec_create_event_poller(ec); > > + if (ret) > > + return ret; > > status = acpi_install_gpe_handler(NULL, ec->gpe, > > ACPI_GPE_EDGE_TRIGGERED, > > &acpi_ec_gpe_handler, ec); > > - if (ACPI_FAILURE(status)) > > + if (ACPI_FAILURE(status)) { > > + ec_delete_event_poller(ec); > > return -ENODEV; > > + } > > > > acpi_ec_start(ec); > > status = acpi_install_address_space_handler(ec->handle, > > @@ -968,6 +1058,7 @@ static int ec_install_handlers(struct acpi_ec *ec) > > acpi_ec_stop(ec); > > acpi_remove_gpe_handler(NULL, ec->gpe, > > &acpi_ec_gpe_handler); > > + ec_delete_event_poller(ec); > > return -ENODEV; > > } > > } > > @@ -985,6 +1076,7 @@ static void ec_remove_handlers(struct acpi_ec *ec) > > if (ACPI_FAILURE(acpi_remove_gpe_handler(NULL, ec->gpe, > > &acpi_ec_gpe_handler))) > > pr_err("failed to remove gpe handler\n"); > > + ec_delete_event_poller(ec); > > clear_bit(EC_FLAGS_HANDLERS_INSTALLED, &ec->flags); > > } > > > > @@ -1032,7 +1124,7 @@ static int acpi_ec_add(struct acpi_device *device) > > ret = ec_install_handlers(ec); > > > > /* EC is fully operational, allow queries */ > > - clear_bit(EC_FLAGS_QUERY_PENDING, &ec->flags); > > + acpi_ec_enable_event(ec); > > > > /* Clear stale _Q events if hardware might require that */ > > if (EC_FLAGS_CLEAR_ON_RESUME) { > > diff --git a/drivers/acpi/internal.h b/drivers/acpi/internal.h > > index bbcfe0b..20a569c 100644 > > --- a/drivers/acpi/internal.h > > +++ b/drivers/acpi/internal.h > > @@ -128,6 +128,7 @@ struct acpi_ec { > > struct list_head list; > > struct transaction *curr; > > spinlock_t lock; > > + struct task_struct *thread; > > }; > > > > extern struct acpi_ec *first_ec; > > > > -- > I speak only for myself. > Rafael J. Wysocki, Intel Open Source Technology Center. ��.n��������+%������w��{.n�����{�����ܨ}���Ơz�j:+v�����w����ޙ��&�)ߡ�a����z�ޗ���ݢj��w�f
