Re: [PATCH] don't use flush_tlb_all in suspend time

[Shaohua Li <shaohua.li@intel.com>]

On Thu, 2006-05-18 at 10:31 +0200, Pavel Machek wrote:
> Hi!
> 
> > > > In which case, how's about this?
> > > 
> > > Certainly better, I'd say.
> > > 
> > > > @@ -420,7 +421,14 @@ void zap_low_mappings (void)
> > > >  #else
> > > >  		set_pgd(swapper_pg_dir+i, __pgd(0));
> > > >  #endif
> > > > -	if (cpus_weight(cpu_online_map) == 1)
> > > > +	/*
> > > > +	 * We can be called at suspend/resume time, with local interrupts
> > > > +	 * disabled.  But flush_tlb_all() requires that local interrupts be
> > > > +	 * enabled.
> > > > +	 *
> > > > +	 * Happily, the APs are not yet started, so we can use local_flush_tlb()	 * in that case
> > > > +	 */
> > > > +	if (num_online_cpus() == 1)
> > > >  		local_flush_tlb();
> > > >  	else
> > > >  		flush_tlb_all();
> > > 
> > > But this still scares. It means calling convention is "may enable
> > > interrupts with >1 cpu, may not with == 1 cpu". 
> > Below patch should make things clean. How do you think?
> 
> Nice...
> 
> Could we perhaps reuse swsusp_pg_dir (just make it used for swsusp &
> suspend-to-ram) to save a bit more code? It is in arch/i386/mm/init.c
Ok, I guess this is what you want.

Signed-off-by: Shaohua Li <shaohua.li@intel.com>
---

 linux-2.6.17-rc4-mm1-root/arch/i386/kernel/acpi/sleep.c  |   18 ---------------
 linux-2.6.17-rc4-mm1-root/arch/i386/kernel/acpi/wakeup.S |    2 -
 linux-2.6.17-rc4-mm1-root/arch/i386/mm/init.c            |   15 +-----------
 3 files changed, 3 insertions(+), 32 deletions(-)

diff -puN arch/i386/kernel/acpi/wakeup.S~i386_direct_mapping arch/i386/kernel/acpi/wakeup.S
--- linux-2.6.17-rc4-mm1/arch/i386/kernel/acpi/wakeup.S~i386_direct_mapping	2006-05-16 14:52:37.000000000 +0800
+++ linux-2.6.17-rc4-mm1-root/arch/i386/kernel/acpi/wakeup.S	2006-05-18 07:12:40.000000000 +0800
@@ -56,7 +56,7 @@ wakeup_code:
 1:
 
 	# set up page table
-	movl	$swapper_pg_dir-__PAGE_OFFSET, %eax
+	movl	$swsusp_pg_dir-__PAGE_OFFSET, %eax
 	movl	%eax, %cr3
 
 	testl	$1, real_efer_save_restore - wakeup_code
diff -puN arch/i386/kernel/acpi/sleep.c~i386_direct_mapping arch/i386/kernel/acpi/sleep.c
--- linux-2.6.17-rc4-mm1/arch/i386/kernel/acpi/sleep.c~i386_direct_mapping	2006-05-16 14:52:51.000000000 +0800
+++ linux-2.6.17-rc4-mm1-root/arch/i386/kernel/acpi/sleep.c	2006-05-18 07:11:38.000000000 +0800
@@ -11,30 +11,14 @@
 #include <linux/cpumask.h>
 
 #include <asm/smp.h>
-#include <asm/tlbflush.h>
 
 /* address in low memory of the wakeup routine. */
 unsigned long acpi_wakeup_address = 0;
 unsigned long acpi_video_flags;
 extern char wakeup_start, wakeup_end;
 
-extern void zap_low_mappings(void);
-
 extern unsigned long FASTCALL(acpi_copy_wakeup_routine(unsigned long));
 
-static void init_low_mapping(pgd_t * pgd, int pgd_limit)
-{
-	int pgd_ofs = 0;
-
-	while ((pgd_ofs < pgd_limit)
-	       && (pgd_ofs + USER_PTRS_PER_PGD < PTRS_PER_PGD)) {
-		set_pgd(pgd, *(pgd + USER_PTRS_PER_PGD));
-		pgd_ofs++, pgd++;
-	}
-	WARN_ON(num_online_cpus() != 1);
-	local_flush_tlb();
-}
-
 /**
  * acpi_save_state_mem - save kernel state
  *
@@ -45,7 +29,6 @@ int acpi_save_state_mem(void)
 {
 	if (!acpi_wakeup_address)
 		return 1;
-	init_low_mapping(swapper_pg_dir, USER_PTRS_PER_PGD);
 	memcpy((void *)acpi_wakeup_address, &wakeup_start,
 	       &wakeup_end - &wakeup_start);
 	acpi_copy_wakeup_routine(acpi_wakeup_address);
@@ -58,7 +41,6 @@ int acpi_save_state_mem(void)
  */
 void acpi_restore_state_mem(void)
 {
-	zap_low_mappings();
 }
 
 /**
diff -puN arch/i386/mm/init.c~i386_direct_mapping arch/i386/mm/init.c
--- linux-2.6.17-rc4-mm1/arch/i386/mm/init.c~i386_direct_mapping	2006-05-17 09:03:39.000000000 +0800
+++ linux-2.6.17-rc4-mm1-root/arch/i386/mm/init.c	2006-05-18 07:11:10.000000000 +0800
@@ -386,7 +386,7 @@ static void __init pagetable_init (void)
 #endif
 }
 
-#ifdef CONFIG_SOFTWARE_SUSPEND
+#if defined(CONFIG_SOFTWARE_SUSPEND) || defined(CONFIG_ACPI_SLEEP)
 /*
  * Swap suspend & friends need this for resume because things like the intel-agp
  * driver might have split up a kernel 4MB mapping.
@@ -422,18 +422,7 @@ void zap_low_mappings (void)
 #else
 		set_pgd(swapper_pg_dir+i, __pgd(0));
 #endif
-	/*
-	 * We can be called at suspend/resume time, with local interrupts
-	 * disabled.  But flush_tlb_all() requires that local interrupts be
-	 * enabled.
-	 *
-	 * Happily, the APs are not yet started, so we can use local_flush_tlb()
-	 * in that case
-	 */
-	if (num_online_cpus() == 1)
-		local_flush_tlb();
-	else
-		flush_tlb_all();
+	flush_tlb_all();
 }
 
 static int disable_nx __initdata = 0;
_