Messages in this thread Patch in this message | | | Date | Mon, 27 Dec 2004 14:28:29 +0800 | From | Bernard Blackham <> | Subject | [PATCH] sched-fix-scheduling-latencies-in-mttrc reenables interrupts |
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Hi Ingo & Andrew,
The patch sched-fix-scheduling-latencies-in-mttr in recent -mm kernels has the bad side-effect of re-enabling interrupts even if they were disabled. This caused bugs in Software Suspend 2 which reenabled MTRRs whilst interrupts were already disabled.
Attached is a replacement patch which uses spin_lock_irqsave instead of spin_lock_irq.
Kind regards,
Bernard.
-- Bernard Blackham <bernard at blackham dot com dot au> --- linux-2.6.10/arch/i386/kernel/cpu/mtrr/generic.c.orig 2004-10-19 05:54:32.000000000 +0800 +++ linux-2.6.10/arch/i386/kernel/cpu/mtrr/generic.c 2004-12-26 18:20:17.000000000 +0800 @@ -232,6 +232,7 @@ static unsigned long set_mtrr_state(u32 static unsigned long cr4 = 0; static u32 deftype_lo, deftype_hi; static spinlock_t set_atomicity_lock = SPIN_LOCK_UNLOCKED; +static unsigned long sal_flags; static void prepare_set(void) { @@ -240,11 +241,14 @@ static void prepare_set(void) /* Note that this is not ideal, since the cache is only flushed/disabled for this CPU while the MTRRs are changed, but changing this requires more invasive changes to the way the kernel boots */ - spin_lock(&set_atomicity_lock); + /* + * Since we are disabling the cache dont allow any interrupts - they + * would run extremely slow and would only increase the pain: + */ + spin_lock_irqsave(&set_atomicity_lock, sal_flags); /* Enter the no-fill (CD=1, NW=0) cache mode and flush caches. */ cr0 = read_cr0() | 0x40000000; /* set CD flag */ - wbinvd(); write_cr0(cr0); wbinvd(); @@ -266,8 +270,7 @@ static void prepare_set(void) static void post_set(void) { - /* Flush caches and TLBs */ - wbinvd(); + /* Flush TLBs (no need to flush caches - they are disabled) */ __flush_tlb(); /* Intel (P6) standard MTRRs */ @@ -279,7 +282,7 @@ static void post_set(void) /* Restore value of CR4 */ if ( cpu_has_pge ) write_cr4(cr4); - spin_unlock(&set_atomicity_lock); + spin_unlock_irqrestore(&set_atomicity_lock, sal_flags); } static void generic_set_all(void) | |