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authorRafael J. Wysocki <rjw@sisk.pl>2010-03-04 01:52:58 +0100
committerLen Brown <len.brown@intel.com>2010-03-08 14:15:51 -0500
commitf6bb13aa1ea3bb26a4c783822347873f085b9000 (patch)
treee0350530685e0719d4318f052982aa4340a00650 /drivers/acpi/ec.c
parent60b341b778cc2929df16c0a504c91621b3c6a4ad (diff)
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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 <rjw@sisk.pl> Reported-and-tested-by: Maxim Levitsky <maximlevitsky@gmail.com> Signed-off-by: Len Brown <len.brown@intel.com>
Diffstat (limited to 'drivers/acpi/ec.c')
-rw-r--r--drivers/acpi/ec.c33
1 files changed, 32 insertions, 1 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;