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Merge branch 'for-4.19-nmi' into for-linus

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This commit is contained in:
Petr Mladek
2018-08-14 13:36:15 +02:00
parent 554ec50865 03fc7f9c99
commit 9f68cb5791
6 changed files with 87 additions and 48 deletions
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kernel/printk/internal.h
+8 -1
View File
@@ -19,11 +19,16 @@
#ifdef CONFIG_PRINTK
#define PRINTK_SAFE_CONTEXT_MASK 0x3fffffff
#define PRINTK_NMI_DEFERRED_CONTEXT_MASK 0x40000000
#define PRINTK_NMI_DIRECT_CONTEXT_MASK 0x40000000
#define PRINTK_NMI_CONTEXT_MASK 0x80000000
extern raw_spinlock_t logbuf_lock;
__printf(5, 0)
int vprintk_store(int facility, int level,
const char *dict, size_t dictlen,
const char *fmt, va_list args);
__printf(1, 0) int vprintk_default(const char *fmt, va_list args);
__printf(1, 0) int vprintk_deferred(const char *fmt, va_list args);
__printf(1, 0) int vprintk_func(const char *fmt, va_list args);
@@ -54,6 +59,8 @@ void __printk_safe_exit(void);
local_irq_enable(); \
} while (0)
void defer_console_output(void);
#else
__printf(1, 0) int vprintk_func(const char *fmt, va_list args) { return 0; }
kernel/printk/printk.c
+35 -22
View File
@@ -1829,28 +1829,16 @@ static size_t log_output(int facility, int level, enum log_flags lflags, const c
return log_store(facility, level, lflags, 0, dict, dictlen, text, text_len);
}
asmlinkage int vprintk_emit(int facility, int level,
const char *dict, size_t dictlen,
const char *fmt, va_list args)
/* Must be called under logbuf_lock. */
int vprintk_store(int facility, int level,
const char *dict, size_t dictlen,
const char *fmt, va_list args)
{
static char textbuf[LOG_LINE_MAX];
char *text = textbuf;
size_t text_len;
enum log_flags lflags = 0;
unsigned long flags;
int printed_len;
bool in_sched = false;
if (level == LOGLEVEL_SCHED) {
level = LOGLEVEL_DEFAULT;
in_sched = true;
}
boot_delay_msec(level);
printk_delay();
/* This stops the holder of console_sem just where we want him */
logbuf_lock_irqsave(flags);
/*
* The printf needs to come first; we need the syslog
* prefix which might be passed-in as a parameter.
@@ -1894,8 +1882,29 @@ asmlinkage int vprintk_emit(int facility, int level,
if (suppress_message_printing(level))
lflags |= LOG_NOCONS;
printed_len = log_output(facility, level, lflags, dict, dictlen, text, text_len);
return log_output(facility, level, lflags,
dict, dictlen, text, text_len);
}
asmlinkage int vprintk_emit(int facility, int level,
const char *dict, size_t dictlen,
const char *fmt, va_list args)
{
int printed_len;
bool in_sched = false;
unsigned long flags;
if (level == LOGLEVEL_SCHED) {
level = LOGLEVEL_DEFAULT;
in_sched = true;
}
boot_delay_msec(level);
printk_delay();
/* This stops the holder of console_sem just where we want him */
logbuf_lock_irqsave(flags);
printed_len = vprintk_store(facility, level, dict, dictlen, fmt, args);
logbuf_unlock_irqrestore(flags);
/* If called from the scheduler, we can not call up(). */
@@ -2884,16 +2893,20 @@ void wake_up_klogd(void)
preempt_enable();
}
void defer_console_output(void)
{
preempt_disable();
__this_cpu_or(printk_pending, PRINTK_PENDING_OUTPUT);
irq_work_queue(this_cpu_ptr(&wake_up_klogd_work));
preempt_enable();
}
int vprintk_deferred(const char *fmt, va_list args)
{
int r;
r = vprintk_emit(0, LOGLEVEL_SCHED, NULL, 0, fmt, args);
preempt_disable();
__this_cpu_or(printk_pending, PRINTK_PENDING_OUTPUT);
irq_work_queue(this_cpu_ptr(&wake_up_klogd_work));
preempt_enable();
defer_console_output();
return r;
}
kernel/printk/printk_safe.c
+37 -21
View File
@@ -308,24 +308,33 @@ static __printf(1, 0) int vprintk_nmi(const char *fmt, va_list args)
void printk_nmi_enter(void)
{
/*
* The size of the extra per-CPU buffer is limited. Use it only when
* the main one is locked. If this CPU is not in the safe context,
* the lock must be taken on another CPU and we could wait for it.
*/
if ((this_cpu_read(printk_context) & PRINTK_SAFE_CONTEXT_MASK) &&
raw_spin_is_locked(&logbuf_lock)) {
this_cpu_or(printk_context, PRINTK_NMI_CONTEXT_MASK);
} else {
this_cpu_or(printk_context, PRINTK_NMI_DEFERRED_CONTEXT_MASK);
}
this_cpu_or(printk_context, PRINTK_NMI_CONTEXT_MASK);
}
void printk_nmi_exit(void)
{
this_cpu_and(printk_context,
~(PRINTK_NMI_CONTEXT_MASK |
PRINTK_NMI_DEFERRED_CONTEXT_MASK));
this_cpu_and(printk_context, ~PRINTK_NMI_CONTEXT_MASK);
}
/*
* Marks a code that might produce many messages in NMI context
* and the risk of losing them is more critical than eventual
* reordering.
*
* It has effect only when called in NMI context. Then printk()
* will try to store the messages into the main logbuf directly
* and use the per-CPU buffers only as a fallback when the lock
* is not available.
*/
void printk_nmi_direct_enter(void)
{
if (this_cpu_read(printk_context) & PRINTK_NMI_CONTEXT_MASK)
this_cpu_or(printk_context, PRINTK_NMI_DIRECT_CONTEXT_MASK);
}
void printk_nmi_direct_exit(void)
{
this_cpu_and(printk_context, ~PRINTK_NMI_DIRECT_CONTEXT_MASK);
}
#else
@@ -363,6 +372,20 @@ void __printk_safe_exit(void)
__printf(1, 0) int vprintk_func(const char *fmt, va_list args)
{
/*
* Try to use the main logbuf even in NMI. But avoid calling console
* drivers that might have their own locks.
*/
if ((this_cpu_read(printk_context) & PRINTK_NMI_DIRECT_CONTEXT_MASK) &&
raw_spin_trylock(&logbuf_lock)) {
int len;
len = vprintk_store(0, LOGLEVEL_DEFAULT, NULL, 0, fmt, args);
raw_spin_unlock(&logbuf_lock);
defer_console_output();
return len;
}
/* Use extra buffer in NMI when logbuf_lock is taken or in safe mode. */
if (this_cpu_read(printk_context) & PRINTK_NMI_CONTEXT_MASK)
return vprintk_nmi(fmt, args);
@@ -371,13 +394,6 @@ __printf(1, 0) int vprintk_func(const char *fmt, va_list args)
if (this_cpu_read(printk_context) & PRINTK_SAFE_CONTEXT_MASK)
return vprintk_safe(fmt, args);
/*
* Use the main logbuf when logbuf_lock is available in NMI.
* But avoid calling console drivers that might have their own locks.
*/
if (this_cpu_read(printk_context) & PRINTK_NMI_DEFERRED_CONTEXT_MASK)
return vprintk_deferred(fmt, args);
/* No obstacles. */
return vprintk_default(fmt, args);
}