[PATCH RT] scheduling while atomic splats on 3.2-rc4-rt5
From: Clark Williams
Date: Sat Dec 03 2011 - 10:35:51 EST
Thomas,
I was seeing a bunch of scheduling while atomic backtraces from rc4-rt5
on my laptop:
Dec 2 17:50:56 localhost kernel: [ 1397.730931] Call Trace:
Dec 2 17:50:56 localhost kernel: [ 1397.730938] [<ffffffff814d5006>] __schedule_bug+0x75/0x7a
Dec 2 17:50:56 localhost kernel: [ 1397.730943] [<ffffffff814e8e4a>] __schedule+0x8a/0x505
Dec 2 17:50:56 localhost kernel: [ 1397.730947] [<ffffffff814e96df>] schedule+0x75/0x91
Dec 2 17:50:56 localhost kernel: [ 1397.730951] [<ffffffff814ea64e>] rt_spin_lock_slowlock+0x182/0x21e
Dec 2 17:50:56 localhost kernel: [ 1397.730954] [<ffffffff814ea5d9>] ? rt_spin_lock_slowlock+0x10d/0x21e
Dec 2 17:50:56 localhost kernel: [ 1397.730961] [<ffffffff81090477>] rt_spin_lock_fastlock.constprop.12+0x24/0x26
Dec 2 17:50:56 localhost kernel: [ 1397.730965] [<ffffffff814eaabb>] rt_spin_lock+0x16/0x3d
Dec 2 17:50:56 localhost kernel: [ 1397.730969] [<ffffffff812acbe3>] advance_transaction+0x31/0x141
Dec 2 17:50:56 localhost kernel: [ 1397.730972] [<ffffffff812ad819>] acpi_ec_gpe_handler+0x3f/0xc0
Dec 2 17:50:56 localhost kernel: [ 1397.730977] [<ffffffff812b862a>] acpi_ev_gpe_dispatch+0xc5/0x13e
Dec 2 17:50:56 localhost kernel: [ 1397.730983] [<ffffffff812b8758>] acpi_ev_gpe_detect+0xb5/0x10d
Dec 2 17:50:56 localhost kernel: [ 1397.730987] [<ffffffff810b5048>] ? irq_thread_fn+0x3a/0x3a
Dec 2 17:50:56 localhost kernel: [ 1397.730990] [<ffffffff812b6d26>] acpi_ev_sci_xrupt_handler+0x22/0x2b
Dec 2 17:50:56 localhost kernel: [ 1397.730994] [<ffffffff812a7a08>] acpi_irq+0x16/0x31
Dec 2 17:50:56 localhost kernel: [ 1397.730996] [<ffffffff810b506d>] irq_forced_thread_fn+0x25/0x46
Dec 2 17:50:56 localhost kernel: [ 1397.730998] [<ffffffff814eb566>] ? _raw_spin_unlock_irq+0x53/0x60
Dec 2 17:50:56 localhost kernel: [ 1397.731001] [<ffffffff810b4f26>] irq_thread+0xa5/0x18d
Dec 2 17:50:56 localhost kernel: [ 1397.731003] [<ffffffff810b4e81>] ? irq_finalize_oneshot+0x19/0x19
Dec 2 17:50:56 localhost kernel: [ 1397.731006] [<ffffffff81077ad2>] kthread+0x99/0xa1
Dec 2 17:50:56 localhost kernel: [ 1397.731009] [<ffffffff814eb8b8>] ? retint_restore_args+0x13/0x13
Dec 2 17:50:56 localhost kernel: [ 1397.731014] [<ffffffff814f3984>] kernel_thread_helper+0x4/0x10
Dec 2 17:50:56 localhost kernel: [ 1397.731016] [<ffffffff814eb8b8>] ? retint_restore_args+0x13/0x13
Dec 2 17:50:56 localhost kernel: [ 1397.731019] [<ffffffff81077a39>] ? __init_kthread_worker+0x89/0x89
Dec 2 17:50:56 localhost kernel: [ 1397.731022] [<ffffffff814f3980>] ? gs_change+0x13/0x13
The attached patch converts the ACPI Embedded Controller lock to a raw
spinlock. Boots and suspends/resumes with no backtraces (from this
anyway...let's not talk about nouveau right now...)
Clark
commit 03981ccbd4b3d368aa227aa55961f8481e9e645c
Author: Clark Williams <williams@xxxxxxxxxx>
Date: Sat Dec 3 09:15:46 2011 -0600
convert ACPI embedded controller lock to raw spinlock
Was seeing multiple "scheduling while atomic" backtraces on the
3.2-rc2-rt5 realtime kernel. This patch converts the spinlock in
the ACPI embedded controller structure (curr_lock) to be a raw
spinlock.
Signed-off-by: Clark Williams <williams@xxxxxxxxxx>
diff --git a/drivers/acpi/ec.c b/drivers/acpi/ec.c
index b19a18d..5812e01 100644
--- a/drivers/acpi/ec.c
+++ b/drivers/acpi/ec.c
@@ -152,10 +152,10 @@ static int ec_transaction_done(struct acpi_ec *ec)
{
unsigned long flags;
int ret = 0;
- spin_lock_irqsave(&ec->curr_lock, flags);
+ raw_spin_lock_irqsave(&ec->curr_lock, flags);
if (!ec->curr || ec->curr->done)
ret = 1;
- spin_unlock_irqrestore(&ec->curr_lock, flags);
+ raw_spin_unlock_irqrestore(&ec->curr_lock, flags);
return ret;
}
@@ -169,7 +169,7 @@ static void start_transaction(struct acpi_ec *ec)
static void advance_transaction(struct acpi_ec *ec, u8 status)
{
unsigned long flags;
- spin_lock_irqsave(&ec->curr_lock, flags);
+ raw_spin_lock_irqsave(&ec->curr_lock, flags);
if (!ec->curr)
goto unlock;
if (ec->curr->wlen > ec->curr->wi) {
@@ -194,7 +194,7 @@ err:
if (in_interrupt())
++ec->curr->irq_count;
unlock:
- spin_unlock_irqrestore(&ec->curr_lock, flags);
+ raw_spin_unlock_irqrestore(&ec->curr_lock, flags);
}
static int acpi_ec_sync_query(struct acpi_ec *ec);
@@ -232,9 +232,9 @@ static int ec_poll(struct acpi_ec *ec)
if (acpi_ec_read_status(ec) & ACPI_EC_FLAG_IBF)
break;
pr_debug(PREFIX "controller reset, restart transaction\n");
- spin_lock_irqsave(&ec->curr_lock, flags);
+ raw_spin_lock_irqsave(&ec->curr_lock, flags);
start_transaction(ec);
- spin_unlock_irqrestore(&ec->curr_lock, flags);
+ raw_spin_unlock_irqrestore(&ec->curr_lock, flags);
}
return -ETIME;
}
@@ -247,17 +247,17 @@ static int acpi_ec_transaction_unlocked(struct acpi_ec *ec,
if (EC_FLAGS_MSI)
udelay(ACPI_EC_MSI_UDELAY);
/* start transaction */
- spin_lock_irqsave(&ec->curr_lock, tmp);
+ raw_spin_lock_irqsave(&ec->curr_lock, tmp);
/* following two actions should be kept atomic */
ec->curr = t;
start_transaction(ec);
if (ec->curr->command == ACPI_EC_COMMAND_QUERY)
clear_bit(EC_FLAGS_QUERY_PENDING, &ec->flags);
- spin_unlock_irqrestore(&ec->curr_lock, tmp);
+ raw_spin_unlock_irqrestore(&ec->curr_lock, tmp);
ret = ec_poll(ec);
- spin_lock_irqsave(&ec->curr_lock, tmp);
+ raw_spin_lock_irqsave(&ec->curr_lock, tmp);
ec->curr = NULL;
- spin_unlock_irqrestore(&ec->curr_lock, tmp);
+ raw_spin_unlock_irqrestore(&ec->curr_lock, tmp);
return ret;
}
@@ -678,7 +678,7 @@ static struct acpi_ec *make_acpi_ec(void)
mutex_init(&ec->lock);
init_waitqueue_head(&ec->wait);
INIT_LIST_HEAD(&ec->list);
- spin_lock_init(&ec->curr_lock);
+ raw_spin_lock_init(&ec->curr_lock);
return ec;
}
diff --git a/drivers/acpi/internal.h b/drivers/acpi/internal.h
index ca75b9c..68ed95f 100644
--- a/drivers/acpi/internal.h
+++ b/drivers/acpi/internal.h
@@ -62,7 +62,7 @@ struct acpi_ec {
wait_queue_head_t wait;
struct list_head list;
struct transaction *curr;
- spinlock_t curr_lock;
+ raw_spinlock_t curr_lock;
};
extern struct acpi_ec *first_ec;
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