From f6bb13aa1ea3bb26a4c783822347873f085b9000 Mon Sep 17 00:00:00 2001 From: "Rafael J. Wysocki" Date: Thu, 4 Mar 2010 01:52:58 +0100 Subject: [PATCH] ACPI / EC / PM: Close race between EC and resume from hibernation There is a race between resume from hibernation and the EC driver that may result in restoring the hibernation image in the middle of an EC transaction in progress, which in turn may lead to unpredictable behavior of the platform. To remove that race condition, add a helpers for suspending and resuming EC transactions in a safe way to be executed by the ACPI platform hibernate pre-restore and restore cleanup callbacks. http://bugzilla.kernel.org/show_bug.cgi?id=14668 Signed-off-by: Rafael J. Wysocki Reported-and-tested-by: Maxim Levitsky Signed-off-by: Len Brown --- drivers/acpi/ec.c | 33 ++++++++++++++++++++++++++++++++- drivers/acpi/internal.h | 2 ++ drivers/acpi/sleep.c | 19 ++++++++++++++----- 3 files changed, 48 insertions(+), 6 deletions(-) diff --git a/drivers/acpi/ec.c b/drivers/acpi/ec.c index d6471bb6852f..19f93e114225 100644 --- a/drivers/acpi/ec.c +++ b/drivers/acpi/ec.c @@ -76,8 +76,9 @@ enum ec_command { enum { EC_FLAGS_QUERY_PENDING, /* Query is pending */ EC_FLAGS_GPE_STORM, /* GPE storm detected */ - EC_FLAGS_HANDLERS_INSTALLED /* Handlers for GPE and + EC_FLAGS_HANDLERS_INSTALLED, /* Handlers for GPE and * OpReg are installed */ + EC_FLAGS_FROZEN, /* Transactions are suspended */ }; /* If we find an EC via the ECDT, we need to keep a ptr to its context */ @@ -291,6 +292,10 @@ static int acpi_ec_transaction(struct acpi_ec *ec, struct transaction *t) if (t->rdata) memset(t->rdata, 0, t->rlen); mutex_lock(&ec->lock); + if (test_bit(EC_FLAGS_FROZEN, &ec->flags)) { + status = -EINVAL; + goto unlock; + } if (ec->global_lock) { status = acpi_acquire_global_lock(ACPI_EC_UDELAY_GLK, &glk); if (ACPI_FAILURE(status)) { @@ -445,6 +450,32 @@ int ec_transaction(u8 command, EXPORT_SYMBOL(ec_transaction); +void acpi_ec_suspend_transactions(void) +{ + struct acpi_ec *ec = first_ec; + + if (!ec) + return; + + mutex_lock(&ec->lock); + /* Prevent transactions from being carried out */ + set_bit(EC_FLAGS_FROZEN, &ec->flags); + mutex_unlock(&ec->lock); +} + +void acpi_ec_resume_transactions(void) +{ + struct acpi_ec *ec = first_ec; + + if (!ec) + return; + + mutex_lock(&ec->lock); + /* Allow transactions to be carried out again */ + clear_bit(EC_FLAGS_FROZEN, &ec->flags); + mutex_unlock(&ec->lock); +} + static int acpi_ec_query_unlocked(struct acpi_ec *ec, u8 * data) { int result; diff --git a/drivers/acpi/internal.h b/drivers/acpi/internal.h index cb28e0502acc..78742460f1fc 100644 --- a/drivers/acpi/internal.h +++ b/drivers/acpi/internal.h @@ -51,6 +51,8 @@ void acpi_early_processor_set_pdc(void); int acpi_ec_init(void); int acpi_ec_ecdt_probe(void); int acpi_boot_ec_enable(void); +void acpi_ec_suspend_transactions(void); +void acpi_ec_resume_transactions(void); /*-------------------------------------------------------------------------- Suspend/Resume diff --git a/drivers/acpi/sleep.c b/drivers/acpi/sleep.c index 79d33d908b5a..f01f8e84fd3d 100644 --- a/drivers/acpi/sleep.c +++ b/drivers/acpi/sleep.c @@ -552,8 +552,17 @@ static void acpi_hibernation_leave(void) hibernate_nvs_restore(); } -static void acpi_pm_enable_gpes(void) +static int acpi_pm_pre_restore(void) { + acpi_disable_all_gpes(); + acpi_os_wait_events_complete(NULL); + acpi_ec_suspend_transactions(); + return 0; +} + +static void acpi_pm_restore_cleanup(void) +{ + acpi_ec_resume_transactions(); acpi_enable_all_runtime_gpes(); } @@ -565,8 +574,8 @@ static struct platform_hibernation_ops acpi_hibernation_ops = { .prepare = acpi_pm_prepare, .enter = acpi_hibernation_enter, .leave = acpi_hibernation_leave, - .pre_restore = acpi_pm_disable_gpes, - .restore_cleanup = acpi_pm_enable_gpes, + .pre_restore = acpi_pm_pre_restore, + .restore_cleanup = acpi_pm_restore_cleanup, }; /** @@ -618,8 +627,8 @@ static struct platform_hibernation_ops acpi_hibernation_ops_old = { .prepare = acpi_pm_disable_gpes, .enter = acpi_hibernation_enter, .leave = acpi_hibernation_leave, - .pre_restore = acpi_pm_disable_gpes, - .restore_cleanup = acpi_pm_enable_gpes, + .pre_restore = acpi_pm_pre_restore, + .restore_cleanup = acpi_pm_restore_cleanup, .recover = acpi_pm_finish, }; #endif /* CONFIG_HIBERNATION */ -- 2.39.5