@@ -165,16 +165,17 @@ static int ec_transaction_completed(struct acpi_ec *ec)
unsigned long flags;
int ret = 0;
spin_lock_irqsave(&ec->lock, flags);
- if (!ec->curr || (ec->curr->flags & ACPI_EC_COMMAND_COMPLETE))
+ if (ec->curr && (ec->curr->flags & ACPI_EC_COMMAND_COMPLETE))
ret = 1;
spin_unlock_irqrestore(&ec->lock, flags);
return ret;
}
-static void advance_transaction(struct acpi_ec *ec)
+static bool advance_transaction(struct acpi_ec *ec)
{
struct transaction *t;
u8 status;
+ bool wakeup = false;
pr_debug("===== %s =====\n", in_interrupt() ? "IRQ" : "TASK");
status = acpi_ec_read_status(ec);
@@ -190,21 +191,25 @@ static void advance_transaction(struct acpi_ec *ec)
} else if (t->rlen > t->ri) {
if ((status & ACPI_EC_FLAG_OBF) == 1) {
t->rdata[t->ri++] = acpi_ec_read_data(ec);
- if (t->rlen == t->ri)
+ if (t->rlen == t->ri) {
t->flags |= ACPI_EC_COMMAND_COMPLETE;
+ wakeup = true;
+ }
} else
goto err;
} else if (t->wlen == t->wi &&
- (status & ACPI_EC_FLAG_IBF) == 0)
+ (status & ACPI_EC_FLAG_IBF) == 0) {
t->flags |= ACPI_EC_COMMAND_COMPLETE;
- return;
+ wakeup = true;
+ }
+ return wakeup;
} else {
if ((status & ACPI_EC_FLAG_IBF) == 0) {
acpi_ec_write_cmd(ec, t->command);
t->flags |= ACPI_EC_COMMAND_POLL;
} else
goto err;
- return;
+ return wakeup;
}
err:
/*
@@ -215,13 +220,14 @@ err:
if (in_interrupt() && t)
++t->irq_count;
}
+ return wakeup;
}
static void start_transaction(struct acpi_ec *ec)
{
ec->curr->irq_count = ec->curr->wi = ec->curr->ri = 0;
ec->curr->flags = 0;
- advance_transaction(ec);
+ (void)advance_transaction(ec);
}
static int acpi_ec_sync_query(struct acpi_ec *ec, u8 *data);
@@ -255,7 +261,7 @@ static int ec_poll(struct acpi_ec *ec)
return 0;
}
spin_lock_irqsave(&ec->lock, flags);
- advance_transaction(ec);
+ (void)advance_transaction(ec);
spin_unlock_irqrestore(&ec->lock, flags);
} while (time_before(jiffies, delay));
pr_debug(PREFIX "controller reset, restart transaction\n");
@@ -654,12 +660,10 @@ static u32 acpi_ec_gpe_handler(acpi_handle gpe_device,
struct acpi_ec *ec = data;
spin_lock_irqsave(&ec->lock, flags);
- advance_transaction(ec);
- spin_unlock_irqrestore(&ec->lock, flags);
- if (ec_transaction_completed(ec)) {
+ if (advance_transaction(ec))
wake_up(&ec->wait);
- ec_check_sci(ec, acpi_ec_read_status(ec));
- }
+ spin_unlock_irqrestore(&ec->lock, flags);
+ ec_check_sci(ec, acpi_ec_read_status(ec));
return ACPI_INTERRUPT_HANDLED | ACPI_REENABLE_GPE;
}
This is a note to let you know that I have just added a patch titled ACPI / EC: Fix race condition in ec_transaction_completed() to the linux-3.11.y-queue branch of the 3.11.y.z extended stable tree which can be found at: http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.11.y-queue If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.11.y.z tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Luis ------ From 8312e39aa807036e1b2be0c5caf4381d1a8fb43d Mon Sep 17 00:00:00 2001 From: Lv Zheng <lv.zheng@intel.com> Date: Sun, 15 Jun 2014 08:42:07 +0800 Subject: [PATCH 21/41] ACPI / EC: Fix race condition in ec_transaction_completed() commit c0d653412fc8450370167a3268b78fc772ff9c87 upstream. There is a race condition in ec_transaction_completed(). When ec_transaction_completed() is called in the GPE handler, it could return true because of (ec->curr == NULL). Then the wake_up() invocation could complete the next command unexpectedly since there is no lock between the 2 invocations. With the previous cleanup, the IBF=0 waiter race need not be handled any more. It's now safe to return a flag from advance_condition() to indicate the requirement of wakeup, the flag is returned from a locked context. The ec_transaction_completed() is now only invoked by the ec_poll() where the ec->curr is ensured to be different from NULL. After cleaning up, the EVT_SCI=1 check should be moved out of the wakeup condition so that an EVT_SCI raised with (ec->curr == NULL) can trigger a QR_SC command. Link: https://bugzilla.kernel.org/show_bug.cgi?id=70891 Link: https://bugzilla.kernel.org/show_bug.cgi?id=63931 Link: https://bugzilla.kernel.org/show_bug.cgi?id=59911 Reported-and-tested-by: Gareth Williams <gareth@garethwilliams.me.uk> Reported-and-tested-by: Hans de Goede <jwrdegoede@fedoraproject.org> Reported-by: Barton Xu <tank.xuhan@gmail.com> Tested-by: Steffen Weber <steffen.weber@gmail.com> Tested-by: Arthur Chen <axchen@nvidia.com> Signed-off-by: Lv Zheng <lv.zheng@intel.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Signed-off-by: Luis Henriques <luis.henriques@canonical.com> --- drivers/acpi/ec.c | 30 +++++++++++++++++------------- 1 file changed, 17 insertions(+), 13 deletions(-) -- 1.9.1