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Subject[PATCH v2] printk: ignore recursion_bug flag in HW error handle process
From: ShuoX Liu <shuox.liu@intel.com>

When MCE happens in printk, we ignore recursion_bug to make sure MCE logs printed out.

According to Boris' suggestion, we add some helper functions.
1) hw_error_enter: Call it when specific arch begins to process a hardware error.
2) hw_error_exit: Call it when specific arch finishes the processing of a hardware error.
3) in_hw_error():indicates whether HW error handling is in processing.

Each arch could call the helpers in their arch-dependent HW error handlers.

Signed-off-by: Yanmin Zhang <yanmin_zhang@linux.intel.com>
Signed-off-by: ShuoX Liu <shuox.liu@intel.com>
---
arch/x86/include/asm/mce.h | 2 --
arch/x86/kernel/cpu/mcheck/mce.c | 6 ++----
include/linux/cpu.h | 17 +++++++++++++++++
kernel/cpu.c | 3 +++
kernel/printk.c | 3 ++-
5 files changed, 24 insertions(+), 7 deletions(-)
diff --git a/arch/x86/include/asm/mce.h b/arch/x86/include/asm/mce.h
index 441520e..aeda4cc 100644
--- a/arch/x86/include/asm/mce.h
+++ b/arch/x86/include/asm/mce.h
@@ -187,8 +187,6 @@ int mce_available(struct cpuinfo_x86 *c);
DECLARE_PER_CPU(unsigned, mce_exception_count);
DECLARE_PER_CPU(unsigned, mce_poll_count);

-extern atomic_t mce_entry;
-
typedef DECLARE_BITMAP(mce_banks_t, MAX_NR_BANKS);
DECLARE_PER_CPU(mce_banks_t, mce_poll_banks);

diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c
index 2afcbd2..aaf41d2 100644
--- a/arch/x86/kernel/cpu/mcheck/mce.c
+++ b/arch/x86/kernel/cpu/mcheck/mce.c
@@ -61,8 +61,6 @@ int mce_disabled __read_mostly;

#define SPINUNIT 100 /* 100ns */

-atomic_t mce_entry;
-
DEFINE_PER_CPU(unsigned, mce_exception_count);

/*
@@ -1015,7 +1013,7 @@ void do_machine_check(struct pt_regs *regs, long error_code)
DECLARE_BITMAP(toclear, MAX_NR_BANKS);
char *msg = "Unknown";

- atomic_inc(&mce_entry);
+ hw_error_enter();

this_cpu_inc(mce_exception_count);

@@ -1143,7 +1141,7 @@ void do_machine_check(struct pt_regs *regs, long error_code)
mce_report_event(regs);
mce_wrmsrl(MSR_IA32_MCG_STATUS, 0);
out:
- atomic_dec(&mce_entry);
+ hw_error_exit();
sync_core();
}
EXPORT_SYMBOL_GPL(do_machine_check);
diff --git a/include/linux/cpu.h b/include/linux/cpu.h
index 7230bb5..beb56d0 100644
--- a/include/linux/cpu.h
+++ b/include/linux/cpu.h
@@ -210,4 +210,21 @@ static inline int disable_nonboot_cpus(void) { return 0; }
static inline void enable_nonboot_cpus(void) {}
#endif /* !CONFIG_PM_SLEEP_SMP */

+/* HW error handle status helpers */
+extern atomic_t hw_error;
+static inline void hw_error_enter(void)
+{
+ atomic_inc(&hw_error);
+}
+
+static inline void hw_error_exit(void)
+{
+ atomic_dec(&hw_error);
+}
+
+static inline int in_hw_error(void)
+{
+ return atomic_read(&hw_error);
+}
+
#endif /* _LINUX_CPU_H_ */
diff --git a/kernel/cpu.c b/kernel/cpu.c
index 0e6353c..54b9c1f 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -679,3 +679,6 @@ void init_cpu_online(const struct cpumask *src)
{
cpumask_copy(to_cpumask(cpu_online_bits), src);
}
+
+/* hardware error status */
+atomic_t hw_error __read_mostly = ATOMIC_INIT(0);
diff --git a/kernel/printk.c b/kernel/printk.c
index 32462d2..6f0f216 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -1295,7 +1295,8 @@ asmlinkage int vprintk_emit(int facility, int level,
* recursion and return - but flag the recursion so that
* it can be printed at the next appropriate moment:
*/
- if (!oops_in_progress && !lockdep_recursing(current)) {
+ if (!oops_in_progress && !in_hw_error()
+ && !lockdep_recursing(current)) {
recursion_bug = 1;
goto out_restore_irqs;
}
--
1.7.1

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