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Commit e5299926 authored by Hidetoshi Seto's avatar Hidetoshi Seto Committed by Ingo Molnar
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x86: MCE: make cmci_discover_lock irq-safe 



Lockdep reports the warning below when Li tries to offline one cpu:

[  110.835487] =================================
[  110.835616] [ INFO: inconsistent lock state ]
[  110.835688] 2.6.30-rc4-00336-g8c9ed89 #52
[  110.835757] ---------------------------------
[  110.835828] inconsistent {HARDIRQ-ON-W} -> {IN-HARDIRQ-W} usage.
[  110.835908] swapper/0 [HC1[1]:SC0[0]:HE0:SE1] takes:
[  110.835982]  (cmci_discover_lock){?.+...}, at: [<ffffffff80236dc0>] cmci_clear+0x30/0x9b

cmci_clear() can be called via smp_call_function_single().

It is better to disable interrupt while holding cmci_discover_lock,
to turn it into an irq-safe lock - we can deadlock otherwise.

[ Impact: fix possible deadlock in the MCE code ]

Reported-by: default avatarShaohua Li <shaohua.li@intel.com>
Signed-off-by: default avatarHidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
LKML-Reference: <4A03ED38.8000700@jp.fujitsu.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Reported-by: default avatarShaohua <Li&lt;shaohua.li@intel.com>
parent 33df4db0

arch/x86/kernel/cpu/mcheck/mce_intel_64.c

+6 −4
Original line number Original line Diff line number Diff line
@@ -151,10 +151,11 @@ static void print_update(char *type, int *hdr, int num) 
static void cmci_discover(int banks, int boot)

static void cmci_discover(int banks, int boot)

{

{

	unsigned long *owned = (void *)&__get_cpu_var(mce_banks_owned);

	unsigned long *owned = (void *)&__get_cpu_var(mce_banks_owned);

	unsigned long flags;

	int hdr = 0;

	int hdr = 0;

	int i;

	int i;





	spin_lock(&cmci_discover_lock);

	spin_lock_irqsave(&cmci_discover_lock, flags);

	for (i = 0; i < banks; i++) {

	for (i = 0; i < banks; i++) {

		u64 val;

		u64 val;
@@ -184,7 +185,7 @@ static void cmci_discover(int banks, int boot) 
			WARN_ON(!test_bit(i, __get_cpu_var(mce_poll_banks)));

			WARN_ON(!test_bit(i, __get_cpu_var(mce_poll_banks)));

		}

		}

	}

	}

	spin_unlock(&cmci_discover_lock);

	spin_unlock_irqrestore(&cmci_discover_lock, flags);

	if (hdr)

	if (hdr)

		printk(KERN_CONT "\n");

		printk(KERN_CONT "\n");

}

}
@@ -211,13 +212,14 @@ void cmci_recheck(void) 
 */

 */

void cmci_clear(void)

void cmci_clear(void)

{

{

	unsigned long flags;

	int i;

	int i;

	int banks;

	int banks;

	u64 val;

	u64 val;





	if (!cmci_supported(&banks))

	if (!cmci_supported(&banks))

		return;

		return;

	spin_lock(&cmci_discover_lock);

	spin_lock_irqsave(&cmci_discover_lock, flags);

	for (i = 0; i < banks; i++) {

	for (i = 0; i < banks; i++) {

		if (!test_bit(i, __get_cpu_var(mce_banks_owned)))

		if (!test_bit(i, __get_cpu_var(mce_banks_owned)))

			continue;

			continue;
@@ -227,7 +229,7 @@ void cmci_clear(void) 
		wrmsrl(MSR_IA32_MC0_CTL2 + i, val);

		wrmsrl(MSR_IA32_MC0_CTL2 + i, val);

		__clear_bit(i, __get_cpu_var(mce_banks_owned));

		__clear_bit(i, __get_cpu_var(mce_banks_owned));

	}

	}

	spin_unlock(&cmci_discover_lock);

	spin_unlock_irqrestore(&cmci_discover_lock, flags);

}

}





/*

/*