From: Rafael J. Wysocki rafael.j.wysocki@intel.com
[ Upstream commit 4a9af6cac050dce2e895ec3205c4615383ad9112 ]
The flushing of pending work in the EC driver uses drain_workqueue() to flush the event handling work that can requeue itself via advance_transaction(), but this is problematic, because that work may also be requeued from the query workqueue.
Namely, if an EC transaction is carried out during the execution of a query handler, it involves calling advance_transaction() which may queue up the event handling work again. This causes the kernel to complain about attempts to add a work item to the EC event workqueue while it is being drained and worst-case it may cause a valid event to be skipped.
To avoid this problem, introduce two new counters, events_in_progress and queries_in_progress, incremented when a work item is queued on the event workqueue or the query workqueue, respectively, and decremented at the end of the corresponding work function, and make acpi_ec_dispatch_gpe() the workqueues in a loop until the both of these counters are zero (or system wakeup is pending) instead of calling acpi_ec_flush_work().
At the same time, change __acpi_ec_flush_work() to call flush_workqueue() instead of drain_workqueue() to flush the event workqueue.
While at it, use the observation that the work item queued in acpi_ec_query() cannot be pending at that time, because it is used only once, to simplify the code in there.
Additionally, clean up a comment in acpi_ec_query() and adjust white space in acpi_ec_event_processor().
Fixes: f0ac20c3f613 ("ACPI: EC: Fix flushing of pending work") Signed-off-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/acpi/ec.c | 57 +++++++++++++++++++++++++++++++---------- drivers/acpi/internal.h | 2 ++ 2 files changed, 45 insertions(+), 14 deletions(-)
diff --git a/drivers/acpi/ec.c b/drivers/acpi/ec.c index 258a8df235cfb..e5b92958c299e 100644 --- a/drivers/acpi/ec.c +++ b/drivers/acpi/ec.c @@ -167,6 +167,7 @@ struct acpi_ec_query { struct transaction transaction; struct work_struct work; struct acpi_ec_query_handler *handler; + struct acpi_ec *ec; };
static int acpi_ec_query(struct acpi_ec *ec, u8 *data); @@ -462,6 +463,7 @@ static void acpi_ec_submit_query(struct acpi_ec *ec) ec_dbg_evt("Command(%s) submitted/blocked", acpi_ec_cmd_string(ACPI_EC_COMMAND_QUERY)); ec->nr_pending_queries++; + ec->events_in_progress++; queue_work(ec_wq, &ec->work); } } @@ -528,7 +530,7 @@ static void acpi_ec_enable_event(struct acpi_ec *ec) #ifdef CONFIG_PM_SLEEP static void __acpi_ec_flush_work(void) { - drain_workqueue(ec_wq); /* flush ec->work */ + flush_workqueue(ec_wq); /* flush ec->work */ flush_workqueue(ec_query_wq); /* flush queries */ }
@@ -1119,7 +1121,7 @@ void acpi_ec_remove_query_handler(struct acpi_ec *ec, u8 query_bit) } EXPORT_SYMBOL_GPL(acpi_ec_remove_query_handler);
-static struct acpi_ec_query *acpi_ec_create_query(u8 *pval) +static struct acpi_ec_query *acpi_ec_create_query(struct acpi_ec *ec, u8 *pval) { struct acpi_ec_query *q; struct transaction *t; @@ -1127,11 +1129,13 @@ static struct acpi_ec_query *acpi_ec_create_query(u8 *pval) q = kzalloc(sizeof (struct acpi_ec_query), GFP_KERNEL); if (!q) return NULL; + INIT_WORK(&q->work, acpi_ec_event_processor); t = &q->transaction; t->command = ACPI_EC_COMMAND_QUERY; t->rdata = pval; t->rlen = 1; + q->ec = ec; return q; }
@@ -1148,13 +1152,21 @@ static void acpi_ec_event_processor(struct work_struct *work) { struct acpi_ec_query *q = container_of(work, struct acpi_ec_query, work); struct acpi_ec_query_handler *handler = q->handler; + struct acpi_ec *ec = q->ec;
ec_dbg_evt("Query(0x%02x) started", handler->query_bit); + if (handler->func) handler->func(handler->data); else if (handler->handle) acpi_evaluate_object(handler->handle, NULL, NULL, NULL); + ec_dbg_evt("Query(0x%02x) stopped", handler->query_bit); + + spin_lock_irq(&ec->lock); + ec->queries_in_progress--; + spin_unlock_irq(&ec->lock); + acpi_ec_delete_query(q); }
@@ -1164,7 +1176,7 @@ static int acpi_ec_query(struct acpi_ec *ec, u8 *data) int result; struct acpi_ec_query *q;
- q = acpi_ec_create_query(&value); + q = acpi_ec_create_query(ec, &value); if (!q) return -ENOMEM;
@@ -1186,19 +1198,20 @@ static int acpi_ec_query(struct acpi_ec *ec, u8 *data) }
/* - * It is reported that _Qxx are evaluated in a parallel way on - * Windows: + * It is reported that _Qxx are evaluated in a parallel way on Windows: * https://bugzilla.kernel.org/show_bug.cgi?id=94411 * - * Put this log entry before schedule_work() in order to make - * it appearing before any other log entries occurred during the - * work queue execution. + * Put this log entry before queue_work() to make it appear in the log + * before any other messages emitted during workqueue handling. */ ec_dbg_evt("Query(0x%02x) scheduled", value); - if (!queue_work(ec_query_wq, &q->work)) { - ec_dbg_evt("Query(0x%02x) overlapped", value); - result = -EBUSY; - } + + spin_lock_irq(&ec->lock); + + ec->queries_in_progress++; + queue_work(ec_query_wq, &q->work); + + spin_unlock_irq(&ec->lock);
err_exit: if (result) @@ -1256,6 +1269,10 @@ static void acpi_ec_event_handler(struct work_struct *work) ec_dbg_evt("Event stopped");
acpi_ec_check_event(ec); + + spin_lock_irqsave(&ec->lock, flags); + ec->events_in_progress--; + spin_unlock_irqrestore(&ec->lock, flags); }
static u32 acpi_ec_gpe_handler(acpi_handle gpe_device, @@ -1972,6 +1989,7 @@ void acpi_ec_set_gpe_wake_mask(u8 action)
bool acpi_ec_dispatch_gpe(void) { + bool work_in_progress; u32 ret;
if (!first_ec) @@ -1992,8 +2010,19 @@ bool acpi_ec_dispatch_gpe(void) if (ret == ACPI_INTERRUPT_HANDLED) pm_pr_dbg("EC GPE dispatched\n");
- /* Flush the event and query workqueues. */ - acpi_ec_flush_work(); + /* Drain EC work. */ + do { + acpi_ec_flush_work(); + + pm_pr_dbg("ACPI EC work flushed\n"); + + spin_lock_irq(&first_ec->lock); + + work_in_progress = first_ec->events_in_progress + + first_ec->queries_in_progress > 0; + + spin_unlock_irq(&first_ec->lock); + } while (work_in_progress && !pm_wakeup_pending());
return false; } diff --git a/drivers/acpi/internal.h b/drivers/acpi/internal.h index 159c422601bc4..62b6b36f3a37c 100644 --- a/drivers/acpi/internal.h +++ b/drivers/acpi/internal.h @@ -183,6 +183,8 @@ struct acpi_ec { struct work_struct work; unsigned long timestamp; unsigned long nr_pending_queries; + unsigned int events_in_progress; + unsigned int queries_in_progress; bool busy_polling; unsigned int polling_guard; };