Gitweb:     
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=1efc5da3cf567d2f6b795f9d2112ed97fec4ee7c
Commit:     1efc5da3cf567d2f6b795f9d2112ed97fec4ee7c
Parent:     482a579b370a0bf924b577efd6c750284a95e0fb
Author:     Mathieu Desnoyers <[EMAIL PROTECTED]>
AuthorDate: Sat Feb 10 01:46:29 2007 -0800
Committer:  Linus Torvalds <[EMAIL PROTECTED]>
CommitDate: Sun Feb 11 11:18:06 2007 -0800

    [PATCH] order of lockdep off/on in vprintk() should be changed
    
    The order of locking between lockdep_off/on() and local_irq_save/restore() 
in
    vprintk() should be changed.
    
    * In kernel/printk.c :
    
    vprintk() does :
    
    preempt_disable()
    local_irq_save()
    lockdep_off()
    spin_lock(&logbuf_lock)
    spin_unlock(&logbuf_lock)
    if(!down_trylock(&console_sem))
       up(&console_sem)
    lockdep_on()
    local_irq_restore()
    preempt_enable()
    
    The goals here is to make sure we do not call printk() recursively from
    kernel/lockdep.c:__lock_acquire() (called from spin_* and down/up) nor from
    kernel/lockdep.c:trace_hardirqs_on/off() (called from 
local_irq_restore/save).
    It can then potentially call printk() through mark_held_locks/mark_lock.
    
    It correctly protects against the spin_lock call and the up/down call, but 
it
    does not protect against local_irq_restore. It could cause infinite 
recursive
    printk/trace_hardirqs_on() calls when printk() is called from the
    mark_lock() error handing path.
    
    We should change the locking so it becomes correct :
    
    preempt_disable()
    lockdep_off()
    local_irq_save()
    spin_lock(&logbuf_lock)
    spin_unlock(&logbuf_lock)
    if(!down_trylock(&console_sem))
       up(&console_sem)
    local_irq_restore()
    lockdep_on()
    preempt_enable()
    
    Signed-off-by: Mathieu Desnoyers <[EMAIL PROTECTED]>
    Acked-by: Ingo Molnar <[EMAIL PROTECTED]>
    Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
    Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]>
---
 kernel/printk.c |    6 +++---
 1 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/kernel/printk.c b/kernel/printk.c
index 4da26b0..0c15187 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -529,7 +529,7 @@ asmlinkage int vprintk(const char *fmt, va_list args)
                zap_locks();
 
        /* This stops the holder of console_sem just where we want him */
-       local_irq_save(flags);
+       raw_local_irq_save(flags);
        lockdep_off();
        spin_lock(&logbuf_lock);
        printk_cpu = smp_processor_id();
@@ -618,7 +618,7 @@ asmlinkage int vprintk(const char *fmt, va_list args)
                        up(&console_sem);
                }
                lockdep_on();
-               local_irq_restore(flags);
+               raw_local_irq_restore(flags);
        } else {
                /*
                 * Someone else owns the drivers.  We drop the spinlock, which
@@ -628,7 +628,7 @@ asmlinkage int vprintk(const char *fmt, va_list args)
                printk_cpu = UINT_MAX;
                spin_unlock(&logbuf_lock);
                lockdep_on();
-               local_irq_restore(flags);
+               raw_local_irq_restore(flags);
        }
 
        preempt_enable();
-
To unsubscribe from this list: send the line "unsubscribe git-commits-head" in
the body of a message to [EMAIL PROTECTED]
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Reply via email to