[PATH -mm] Fix a race condtion of oops_in_progress

From: Huang Ying
Date: Sun Aug 17 2008 - 22:03:42 EST

This patch fix a race condition of oops_in_progress. Which may be
changed on multiple CPU simultaneously, but it is changed via
non-atomic operation ++/--. This patch changes the definition of
oops_in_process from int to atomic_t, and accessing method to atomic
operations.

This patch is based on 2.6.27-rc1-mm1.

Signed-off-by: Huang Ying <ying.huang@xxxxxxxxx>

---
arch/blackfin/kernel/traps.c | 14 +++++++-------
arch/cris/arch-v32/kernel/time.c | 4 ++--
arch/cris/kernel/traps.c | 6 +++---
arch/cris/mm/fault.c | 6 +++---
arch/ia64/kernel/mca.c | 6 +++---
arch/mn10300/mm/fault.c | 4 ++--
arch/parisc/kernel/traps.c | 4 ++--
arch/s390/kernel/setup.c | 6 +++---
arch/s390/mm/fault.c | 4 ++--
drivers/char/vt.c | 2 +-
drivers/mtd/mtdoops.c | 2 +-
drivers/parisc/led.c | 2 +-
drivers/serial/8250.c | 2 +-
drivers/serial/cpm_uart/cpm_uart_core.c | 2 +-
drivers/serial/sunhv.c | 4 ++--
drivers/serial/sunsab.c | 2 +-
drivers/serial/sunsu.c | 2 +-
drivers/serial/sunzilog.c | 2 +-
drivers/serial/uartlite.c | 4 ++--
drivers/video/aty/radeonfb.h | 2 +-
include/linux/console.h | 3 ++-
include/linux/kernel.h | 4 +++-
kernel/printk.c | 10 +++++-----
kernel/sched.c | 3 ++-
lib/bust_spinlocks.c | 4 ++--
25 files changed, 54 insertions(+), 50 deletions(-)

--- a/lib/bust_spinlocks.c
+++ b/lib/bust_spinlocks.c
@@ -17,12 +17,12 @@
void __attribute__((weak)) bust_spinlocks(int yes)
{
if (yes) {
- ++oops_in_progress;
+ atomic_inc(&oops_in_progress);
} else {
#ifdef CONFIG_VT
unblank_screen();
#endif
- if (--oops_in_progress == 0)
+ if (atomic_dec_and_test(&oops_in_progress))
wake_up_klogd();
}
}
--- a/arch/blackfin/kernel/traps.c
+++ b/arch/blackfin/kernel/traps.c
@@ -183,7 +183,7 @@ done:
asmlinkage void double_fault_c(struct pt_regs *fp)
{
console_verbose();
- oops_in_progress = 1;
+ atomic_set(&oops_in_progress, 1);
printk(KERN_EMERG "\n" KERN_EMERG "Double Fault\n");
dump_bfin_process(fp);
dump_bfin_mem(fp);
@@ -221,11 +221,11 @@ asmlinkage void trap_c(struct pt_regs *f
#endif
){
console_verbose();
- oops_in_progress = 1;
+ atomic_set(&oops_in_progress, 1);
} else if (current) {
if (current->mm == NULL) {
console_verbose();
- oops_in_progress = 1;
+ atomic_set(&oops_in_progress, 1);
}
}

@@ -510,7 +510,7 @@ asmlinkage void trap_c(struct pt_regs *f
#endif
dump_bfin_trace_buffer();

- if (oops_in_progress) {
+ if (atomic_read(&oops_in_progress)) {
/* Dump the current kernel stack */
printk(KERN_NOTICE "\n" KERN_NOTICE "Kernel Stack\n");
show_stack(current, NULL);
@@ -852,7 +852,7 @@ void dump_bfin_process(struct pt_regs *f
* stack all the time, so do this until we fix that */
unsigned int context = bfin_read_IPEND();

- if (oops_in_progress)
+ if (atomic_read(&oops_in_progress))
printk(KERN_EMERG "Kernel OOPS in progress\n");

if (context & 0x0020 && (fp->seqstat & SEQSTAT_EXCAUSE) == VEC_HWERR)
@@ -934,7 +934,7 @@ void dump_bfin_mem(struct pt_regs *fp)

/* Hardware error interrupts can be deferred */
if (unlikely(sti && (fp->seqstat & SEQSTAT_EXCAUSE) == VEC_HWERR &&
- oops_in_progress)){
+ atomic_read(&oops_in_progress))) {
printk(KERN_NOTICE "Looks like this was a deferred error - sorry\n");
#ifndef CONFIG_DEBUG_HWERR
printk(KERN_NOTICE "The remaining message may be meaningless\n"
@@ -1123,7 +1123,7 @@ void panic_cplb_error(int cplb_panic, st
break;
}

- oops_in_progress = 1;
+ atomic_set(&oops_in_progress, 1);

dump_bfin_process(fp);
dump_bfin_mem(fp);
--- a/arch/cris/arch-v32/kernel/time.c
+++ b/arch/cris/arch-v32/kernel/time.c
@@ -170,7 +170,7 @@ handle_watchdog_bite(struct pt_regs* reg
#if defined(CONFIG_ETRAX_WATCHDOG)
extern int cause_of_death;

- oops_in_progress = 1;
+ atomic_set(&oops_in_progress, 1);
printk(KERN_WARNING "Watchdog bite\n");

/* Check if forced restart or unexpected watchdog */
@@ -191,7 +191,7 @@ handle_watchdog_bite(struct pt_regs* reg
stop_watchdog();
printk(KERN_WARNING "Oops: bitten by watchdog\n");
show_registers(regs);
- oops_in_progress = 0;
+ atomic_set(&oops_in_progress, 0);
#ifndef CONFIG_ETRAX_WATCHDOG_NICE_DOGGY
reset_watchdog();
#endif
--- a/arch/cris/kernel/traps.c
+++ b/arch/cris/kernel/traps.c
@@ -164,10 +164,10 @@ void
oops_nmi_handler(struct pt_regs *regs)
{
stop_watchdog();
- oops_in_progress = 1;
+ atomic_set(&oops_in_progress, 1);
printk("NMI!\n");
show_registers(regs);
- oops_in_progress = 0;
+ atomic_set(&oops_in_progress, 0);
}

static int __init
@@ -223,7 +223,7 @@ die_if_kernel(const char *str, struct pt

show_registers(regs);

- oops_in_progress = 0;
+ atomic_set(&oops_in_progress, 0);

#ifdef CONFIG_ETRAX_WATCHDOG_NICE_DOGGY
reset_watchdog();
--- a/arch/cris/mm/fault.c
+++ b/arch/cris/mm/fault.c
@@ -223,8 +223,8 @@ do_page_fault(unsigned long address, str
* terminate things with extreme prejudice.
*/

- if (!oops_in_progress) {
- oops_in_progress = 1;
+ if (!atomic_read(&oops_in_progress)) {
+ atomic_set(&oops_in_progress, 1);
if ((unsigned long) (address) < PAGE_SIZE)
printk(KERN_ALERT "Unable to handle kernel NULL "
"pointer dereference");
@@ -233,7 +233,7 @@ do_page_fault(unsigned long address, str
" at virtual address %08lx\n", address);

die_if_kernel("Oops", regs, (writeaccess << 1) | protection);
- oops_in_progress = 0;
+ atomic_set(&oops_in_progress, 0);
}

do_exit(SIGKILL);
--- a/arch/ia64/kernel/mca.c
+++ b/arch/ia64/kernel/mca.c
@@ -187,7 +187,7 @@ static unsigned long mlogbuf_timestamp =

static int loglevel_save = -1;
#define BREAK_LOGLEVEL(__console_loglevel) \
- oops_in_progress = 1; \
+ atomic_set(&oops_in_progress, 1); \
if (loglevel_save < 0) \
loglevel_save = __console_loglevel; \
__console_loglevel = 15;
@@ -198,7 +198,7 @@ static int loglevel_save = -1;
loglevel_save = -1; \
} \
mlogbuf_finished = 0; \
- oops_in_progress = 0;
+ atomic_set(&oops_in_progress, 0);

/*
* Push messages into buffer, print them later if not urgent.
@@ -215,7 +215,7 @@ void ia64_mca_printk(const char *fmt, ..
va_end(args);

/* Copy the output into mlogbuf */
- if (oops_in_progress) {
+ if (atomic_read(&oops_in_progress)) {
/* mlogbuf was abandoned, use printk directly instead. */
printk(temp_buf);
} else {
--- a/arch/mn10300/mm/fault.c
+++ b/arch/mn10300/mm/fault.c
@@ -39,7 +39,7 @@
void bust_spinlocks(int yes)
{
if (yes) {
- oops_in_progress = 1;
+ atomic_set(&oops_in_progress, 1);
#ifdef CONFIG_SMP
/* Many serial drivers do __global_cli() */
global_irq_lock = 0;
@@ -49,7 +49,7 @@ void bust_spinlocks(int yes)
#ifdef CONFIG_VT
unblank_screen();
#endif
- oops_in_progress = 0;
+ atomic_set(&oops_in_progress, 0);
/*
* OK, the message is on the console. Now we call printk()
* without oops_in_progress set so that printk will give klogd
--- a/arch/parisc/kernel/traps.c
+++ b/arch/parisc/kernel/traps.c
@@ -246,7 +246,7 @@ void die_if_kernel(char *str, struct pt_
return;
}

- oops_in_progress = 1;
+ atomic_set(&oops_in_progress, 1);

/* Amuse the user in a SPARC fashion */
if (err) printk(
@@ -438,7 +438,7 @@ void parisc_terminate(char *msg, struct
{
static DEFINE_SPINLOCK(terminate_lock);

- oops_in_progress = 1;
+ atomic_set(&oops_in_progress, 1);

set_eiem(0);
local_irq_disable();
--- a/arch/s390/kernel/setup.c
+++ b/arch/s390/kernel/setup.c
@@ -240,7 +240,7 @@ static inline void setup_zfcpdump(unsign

void machine_restart(char *command)
{
- if ((!in_interrupt() && !in_atomic()) || oops_in_progress)
+ if ((!in_interrupt() && !in_atomic()) || atomic_read(&oops_in_progress))
/*
* Only unblank the console if we are called in enabled
* context or a bust_spinlocks cleared the way for us.
@@ -251,7 +251,7 @@ void machine_restart(char *command)

void machine_halt(void)
{
- if (!in_interrupt() || oops_in_progress)
+ if (!in_interrupt() || atomic_read(&oops_in_progress))
/*
* Only unblank the console if we are called in enabled
* context or a bust_spinlocks cleared the way for us.
@@ -262,7 +262,7 @@ void machine_halt(void)

void machine_power_off(void)
{
- if (!in_interrupt() || oops_in_progress)
+ if (!in_interrupt() || atomic_read(&oops_in_progress))
/*
* Only unblank the console if we are called in enabled
* context or a bust_spinlocks cleared the way for us.
--- a/arch/s390/mm/fault.c
+++ b/arch/s390/mm/fault.c
@@ -81,11 +81,11 @@ static inline int notify_page_fault(stru
void bust_spinlocks(int yes)
{
if (yes) {
- oops_in_progress = 1;
+ atomic_set(&oops_in_progress, 1);
} else {
int loglevel_save = console_loglevel;
console_unblank();
- oops_in_progress = 0;
+ atomic_set(&oops_in_progress, 0);
/*
* OK, the message is on the console. Now we call printk()
* without oops_in_progress set so that printk will give klogd
--- a/drivers/char/vt.c
+++ b/drivers/char/vt.c
@@ -3639,7 +3639,7 @@ void do_unblank_screen(int leaving_gfx)
* context for the sake of the low level drivers, except in the special
* case of oops_in_progress
*/
- if (!oops_in_progress)
+ if (!atomic_read(&oops_in_progress))
might_sleep();

WARN_CONSOLE_UNLOCKED();
--- a/drivers/mtd/mtdoops.c
+++ b/drivers/mtd/mtdoops.c
@@ -341,7 +341,7 @@ mtdoops_console_write(struct console *co
struct mtd_info *mtd = cxt->mtd;
unsigned long flags;

- if (!oops_in_progress) {
+ if (!atomic_read(&oops_in_progress)) {
mtdoops_console_sync();
return;
}
--- a/drivers/parisc/led.c
+++ b/drivers/parisc/led.c
@@ -464,7 +464,7 @@ static void led_work_func (struct work_s
if (likely(led_diskio)) currentleds |= led_get_diskio_activity();

/* blink all LEDs twice a second if we got an Oops (HPMC) */
- if (unlikely(oops_in_progress))
+ if (unlikely(atomic_read(&oops_in_progress)))
currentleds = (count_HZ<=(HZ/2)) ? 0 : 0xff;

if (currentleds != lastleds)
--- a/drivers/serial/8250.c
+++ b/drivers/serial/8250.c
@@ -2553,7 +2553,7 @@ serial8250_console_write(struct console
if (up->port.sysrq) {
/* serial8250_handle_port() already took the lock */
locked = 0;
- } else if (oops_in_progress) {
+ } else if (atomic_read(&oops_in_progress)) {
locked = spin_trylock(&up->port.lock);
} else
spin_lock(&up->port.lock);
--- a/drivers/serial/cpm_uart/cpm_uart_core.c
+++ b/drivers/serial/cpm_uart/cpm_uart_core.c
@@ -1120,7 +1120,7 @@ static void cpm_uart_console_write(struc
cbd_t __iomem *bdp, *bdbase;
unsigned char *cp;
unsigned long flags;
- int nolock = oops_in_progress;
+ int nolock = atomic_read(&oops_in_progress);

if (unlikely(nolock)) {
local_irq_save(flags);
--- a/drivers/serial/sunhv.c
+++ b/drivers/serial/sunhv.c
@@ -435,7 +435,7 @@ static void sunhv_console_write_paged(st
local_irq_save(flags);
if (port->sysrq) {
locked = 0;
- } else if (oops_in_progress) {
+ } else if (atomic_read(&oops_in_progress)) {
locked = spin_trylock(&port->lock);
} else
spin_lock(&port->lock);
@@ -494,7 +494,7 @@ static void sunhv_console_write_bychar(s
local_irq_save(flags);
if (port->sysrq) {
locked = 0;
- } else if (oops_in_progress) {
+ } else if (atomic_read(&oops_in_progress)) {
locked = spin_trylock(&port->lock);
} else
spin_lock(&port->lock);
--- a/drivers/serial/sunsab.c
+++ b/drivers/serial/sunsab.c
@@ -852,7 +852,7 @@ static void sunsab_console_write(struct
local_irq_save(flags);
if (up->port.sysrq) {
locked = 0;
- } else if (oops_in_progress) {
+ } else if (atomic_read(&oops_in_progress)) {
locked = spin_trylock(&up->port.lock);
} else
spin_lock(&up->port.lock);
--- a/drivers/serial/sunsu.c
+++ b/drivers/serial/sunsu.c
@@ -1296,7 +1296,7 @@ static void sunsu_console_write(struct c
local_irq_save(flags);
if (up->port.sysrq) {
locked = 0;
- } else if (oops_in_progress) {
+ } else if (atomic_read(&oops_in_progress)) {
locked = spin_trylock(&up->port.lock);
} else
spin_lock(&up->port.lock);
--- a/drivers/serial/sunzilog.c
+++ b/drivers/serial/sunzilog.c
@@ -1154,7 +1154,7 @@ sunzilog_console_write(struct console *c
local_irq_save(flags);
if (up->port.sysrq) {
locked = 0;
- } else if (oops_in_progress) {
+ } else if (atomic_read(&oops_in_progress)) {
locked = spin_trylock(&up->port.lock);
} else
spin_lock(&up->port.lock);
--- a/drivers/serial/uartlite.c
+++ b/drivers/serial/uartlite.c
@@ -368,9 +368,9 @@ static void ulite_console_write(struct c
unsigned int ier;
int locked = 1;

- if (oops_in_progress) {
+ if (atomic_read(&oops_in_progress))
locked = spin_trylock_irqsave(&port->lock, flags);
- } else
+ else
spin_lock_irqsave(&port->lock, flags);

/* save and disable interrupt */
--- a/drivers/video/aty/radeonfb.h
+++ b/drivers/video/aty/radeonfb.h
@@ -380,7 +380,7 @@ struct radeonfb_info {
*/
static inline void _radeon_msleep(struct radeonfb_info *rinfo, unsigned long ms)
{
- if (rinfo->no_schedule || oops_in_progress)
+ if (rinfo->no_schedule || atomic_read(&oops_in_progress))
mdelay(ms);
else
msleep(ms);
--- a/include/linux/console.h
+++ b/include/linux/console.h
@@ -142,7 +142,8 @@ void vcs_remove_sysfs(struct tty_struct

/* Some debug stub to catch some of the obvious races in the VT code */
#if 1
-#define WARN_CONSOLE_UNLOCKED() WARN_ON(!is_console_locked() && !oops_in_progress)
+#define WARN_CONSOLE_UNLOCKED() \
+ WARN_ON(!is_console_locked() && !atomic_read(&oops_in_progress))
#else
#define WARN_CONSOLE_UNLOCKED()
#endif
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -18,6 +18,7 @@
#include <linux/ratelimit.h>
#include <asm/byteorder.h>
#include <asm/bug.h>
+#include <asm/atomic.h>

extern const char linux_banner[];
extern const char linux_proc_banner[];
@@ -231,7 +232,8 @@ static inline void console_verbose(void)

extern void bust_spinlocks(int yes);
extern void wake_up_klogd(void);
-extern int oops_in_progress; /* If set, an oops, panic(), BUG() or die() is in progress */
+/* If set, an oops, panic(), BUG() or die() is in progress */
+extern atomic_t oops_in_progress;
extern int panic_timeout;
extern int panic_on_oops;
extern int panic_on_unrecovered_nmi;
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -64,7 +64,7 @@ int console_printk[4] = {
* Low level drivers may need that to know if they can schedule in
* their unblank() callback or not. So let's export it.
*/
-int oops_in_progress;
+atomic_t oops_in_progress;
EXPORT_SYMBOL(oops_in_progress);

/*
@@ -248,7 +248,7 @@ int log_buf_copy(char *dest, int idx, in
int ret, max;
bool took_lock = false;

- if (!oops_in_progress) {
+ if (!atomic_read(&oops_in_progress)) {
spin_lock_irq(&logbuf_lock);
took_lock = true;
}
@@ -688,7 +688,7 @@ asmlinkage int vprintk(const char *fmt,
* recursion and return - but flag the recursion so that
* it can be printed at the next appropriate moment:
*/
- if (!oops_in_progress) {
+ if (!atomic_read(&oops_in_progress)) {
recursion_bug = 1;
goto out_restore_irqs;
}
@@ -984,7 +984,7 @@ int is_console_locked(void)

void wake_up_klogd(void)
{
- if (!oops_in_progress && waitqueue_active(&log_wait))
+ if (!atomic_read(&oops_in_progress) && waitqueue_active(&log_wait))
wake_up_interruptible(&log_wait);
}

@@ -1067,7 +1067,7 @@ void console_unblank(void)
* console_unblank can no longer be called in interrupt context unless
* oops_in_progress is set to 1..
*/
- if (oops_in_progress) {
+ if (atomic_read(&oops_in_progress)) {
if (!down_try(&console_sem))
return;
} else
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -8111,7 +8111,8 @@ void __might_sleep(char *file, int line)
static unsigned long prev_jiffy; /* ratelimiting */

if ((in_atomic() || irqs_disabled()) &&
- system_state == SYSTEM_RUNNING && !oops_in_progress) {
+ system_state == SYSTEM_RUNNING &&
+ !atomic_read(&oops_in_progress)) {
if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy)
return;
prev_jiffy = jiffies;


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