The patch titled
Subject: printk: add interface for disabling recursion check
has been removed from the -mm tree. Its filename was
printk-add-interface-for-disabling-recursion-check.patch
This patch was dropped because an updated version will be merged
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
From: ShuoX Liu <shuox.liu@xxxxxxxxx>
Subject: printk: add interface for disabling recursion check
In some special scenarios such as Machine Check Exception happening during
a printk, we want to bypass the printk recursion check to print some
important information. So we add these interfaces to printk.
1) printk_recursion_check_disable() for disabling recursion check
2) printk_recursion_check_enable() for enabling recursion check
Signed-off-by: Yanmin Zhang <yanmin_zhang@xxxxxxxxxxxxxxx>
Signed-off-by: ShuoX Liu <shuox.liu@xxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxx>
Cc: "Luck, Tony" <tony.luck@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/printk.h | 3 +++
kernel/printk.c | 17 ++++++++++++++++-
2 files changed, 19 insertions(+), 1 deletion(-)
diff -puN include/linux/printk.h~printk-add-interface-for-disabling-recursion-check include/linux/printk.h
--- a/include/linux/printk.h~printk-add-interface-for-disabling-recursion-check
+++ a/include/linux/printk.h
@@ -49,6 +49,9 @@ static inline void console_verbose(void)
console_loglevel = 15;
}
+void printk_recursion_check_disable(void);
+void printk_recursion_check_enable(void);
+
struct va_format {
const char *fmt;
va_list *va;
diff -puN kernel/printk.c~printk-add-interface-for-disabling-recursion-check kernel/printk.c
--- a/kernel/printk.c~printk-add-interface-for-disabling-recursion-check
+++ a/kernel/printk.c
@@ -78,6 +78,19 @@ int console_printk[4] = {
int oops_in_progress;
EXPORT_SYMBOL(oops_in_progress);
+static atomic_t recursion_check_disabled = ATOMIC_INIT(0);
+
+void printk_recursion_check_disable(void)
+{
+ atomic_inc(&recursion_check_disabled);
+}
+
+void printk_recursion_check_enable(void)
+{
+ WARN_ON(atomic_read(&recursion_check_disabled) < 1);
+ atomic_dec(&recursion_check_disabled);
+}
+
/*
* console_sem protects the console_drivers list, and also
* provides serialisation for access to the entire console
@@ -1310,7 +1323,9 @@ asmlinkage int vprintk_emit(int facility
* 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 (!atomic_read(&recursion_check_disabled)
+ && !oops_in_progress
+ && !lockdep_recursing(current)) {
recursion_bug = 1;
goto out_restore_irqs;
}
_
Patches currently in -mm which might be from shuox.liu@xxxxxxxxx are
cpuidle-move-field-disable-from-per-driver-to-per-cpu.patch
x86-mce-use-new-printk-recursion-disabling-interface.patch
x86-mce-use-new-printk-recursion-disabling-interface-fix.patch
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