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xen/mce: schedule a workqueue to avoid sleep in atomic context

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copy_to_user might sleep and print a stack trace if it is executed
in an atomic spinlock context. Like this:

(XEN) CMCI: send CMCI to DOM0 through virq
BUG: sleeping function called from invalid context at /home/konradinux/kernel.h:199
in_atomic(): 1, irqs_disabled(): 0, pid: 4581, name: mcelog
Pid: 4581, comm: mcelog Tainted: G           O 3.5.0-rc1upstream-00003-g149000b-dirty #1
 [<ffffffff8109ad9a>] __might_sleep+0xda/0x100
 [<ffffffff81329b0b>] xen_mce_chrdev_read+0xab/0x140
 [<ffffffff81148945>] vfs_read+0xc5/0x190
 [<ffffffff81148b0c>] sys_read+0x4c/0x90
 [<ffffffff815bd039>] system_call_fastpath+0x16

This patch schedule a workqueue for IRQ handler to poll the data,
and use mutex instead of spinlock, so copy_to_user sleep in atomic
context would not occur.

Reported-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Suggested-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Liu, Jinsong <jinsong.liu@intel.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
This commit is contained in:
Liu, Jinsong 2012-06-12 23:11:16 +08:00 committed by Konrad Rzeszutek Wilk
parent f65c9bb3fb
commit 1b2a05516e
1 changed files with 11 additions and 7 deletions
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18
drivers/xen/mcelog.c
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@ -55,7 +55,7 @@ static struct mc_info g_mi;
static struct mcinfo_logical_cpu *g_physinfo;
static uint32_t ncpus;
static DEFINE_SPINLOCK(mcelog_lock);
static DEFINE_MUTEX(mcelog_lock);
static struct xen_mce_log xen_mcelog = {
.signature = XEN_MCE_LOG_SIGNATURE,
@ -106,7 +106,7 @@ static ssize_t xen_mce_chrdev_read(struct file *filp, char __user *ubuf,
unsigned num;
int i, err;
spin_lock(&mcelog_lock);
mutex_lock(&mcelog_lock);
num = xen_mcelog.next;
@ -130,7 +130,7 @@ static ssize_t xen_mce_chrdev_read(struct file *filp, char __user *ubuf,
err = -EFAULT;
out:
spin_unlock(&mcelog_lock);
mutex_unlock(&mcelog_lock);
return err ? err : buf - ubuf;
}
@ -310,12 +310,11 @@ static int mc_queue_handle(uint32_t flags)
}
/* virq handler for machine check error info*/
static irqreturn_t xen_mce_interrupt(int irq, void *dev_id)
static void xen_mce_work_fn(struct work_struct *work)
{
int err;
unsigned long tmp;
spin_lock_irqsave(&mcelog_lock, tmp);
mutex_lock(&mcelog_lock);
/* urgent mc_info */
err = mc_queue_handle(XEN_MC_URGENT);
@ -330,8 +329,13 @@ static irqreturn_t xen_mce_interrupt(int irq, void *dev_id)
pr_err(XEN_MCELOG
"Failed to handle nonurgent mc_info queue.\n");
spin_unlock_irqrestore(&mcelog_lock, tmp);
mutex_unlock(&mcelog_lock);
}
static DECLARE_WORK(xen_mce_work, xen_mce_work_fn);
static irqreturn_t xen_mce_interrupt(int irq, void *dev_id)
{
schedule_work(&xen_mce_work);
return IRQ_HANDLED;
}