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    Subject[PATH -mm] Fix a race condtion of oops_in_progress
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    Date
    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@intel.com>

    ---
    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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