Messages in this thread Patch in this message | | | Date | Mon, 22 Dec 2003 16:22:37 -0500 | From | Joe Korty <> | Subject | Re: atomic copy_from_user? |
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On Mon, Dec 22, 2003 at 03:55:06PM -0500, Rob Love wrote: > On Mon, 2003-12-22 at 13:26, Joe Korty wrote: > > > Shouldn't the dec_prempt_count() in kunmap_atomic() be followed > > by a preempt_check_resched()??? > > Probably. > > Actually, dec_preempt_count() ought to call preempt_check_resched() > itself. In the case of !CONFIG_PREEMPT, that call would simply optimize > away. > > Attached patch is against 2.6.0. > > Rob Love > > > linux/preempt.h | 1 + > 1 files changed, 1 insertion(+) > > diff -urN include/linux/preempt.h.orig include/linux/preempt.h > --- include/linux/preempt.h.orig 2003-12-22 15:53:11.329113296 -0500 > +++ include/linux/preempt.h 2003-12-22 15:53:51.314034664 -0500 > @@ -18,6 +18,7 @@ > #define dec_preempt_count() \ > do { \ > preempt_count()--; \ > + preempt_check_resched(); \ > } while (0) > > #ifdef CONFIG_PREEMPT
I am guessing that nowdays even when preemption is disabled one can find preempt_count still being used somewhere. Otherwise it would be better to replace all uses of inc_preempt_count() with preempt_disable() and dec_preempt_count() with preempt_enable().
Joe
diff -ura base/arch/i386/mm/highmem.c new/arch/i386/mm/highmem.c --- base/arch/i386/mm/highmem.c 2003-12-17 21:58:56.000000000 -0500 +++ new/arch/i386/mm/highmem.c 2003-12-22 16:16:27.000000000 -0500 @@ -30,7 +30,7 @@ enum fixed_addresses idx; unsigned long vaddr; - inc_preempt_count(); + preempt_disable(); if (page < highmem_start_page) return page_address(page); @@ -53,7 +53,7 @@ enum fixed_addresses idx = type + KM_TYPE_NR*smp_processor_id(); if (vaddr < FIXADDR_START) { // FIXME - dec_preempt_count(); + preempt_enable(); return; } @@ -68,7 +68,7 @@ __flush_tlb_one(vaddr); #endif - dec_preempt_count(); + preempt_enable(); } struct page *kmap_atomic_to_page(void *ptr) diff -ura base/arch/mips/mm/highmem.c new/arch/mips/mm/highmem.c --- base/arch/mips/mm/highmem.c 2003-12-17 21:58:28.000000000 -0500 +++ new/arch/mips/mm/highmem.c 2003-12-22 16:17:28.000000000 -0500 @@ -40,7 +40,7 @@ enum fixed_addresses idx; unsigned long vaddr; - inc_preempt_count(); + preempt_disable(); if (page < highmem_start_page) return page_address(page); @@ -63,7 +63,7 @@ enum fixed_addresses idx = type + KM_TYPE_NR*smp_processor_id(); if (vaddr < FIXADDR_START) { // FIXME - dec_preempt_count(); + preempt_enable(); return; } @@ -78,7 +78,7 @@ local_flush_tlb_one(vaddr); #endif - dec_preempt_count(); + preempt_enable(); } struct page *kmap_atomic_to_page(void *ptr) diff -ura base/arch/sparc/mm/highmem.c new/arch/sparc/mm/highmem.c --- base/arch/sparc/mm/highmem.c 2003-12-17 21:58:28.000000000 -0500 +++ new/arch/sparc/mm/highmem.c 2003-12-22 16:17:02.000000000 -0500 @@ -33,7 +33,7 @@ unsigned long idx; unsigned long vaddr; - inc_preempt_count(); + preempt_disable(); if (page < highmem_start_page) return page_address(page); @@ -68,7 +68,7 @@ unsigned long idx = type + KM_TYPE_NR*smp_processor_id(); if (vaddr < fix_kmap_begin) { // FIXME - dec_preempt_count(); + preempt_enable(); return; } @@ -95,5 +95,5 @@ flush_tlb_all(); #endif #endif - dec_preempt_count(); + preempt_enable(); } diff -ura base/include/asm-ppc/highmem.h new/include/asm-ppc/highmem.h --- base/include/asm-ppc/highmem.h 2003-12-17 21:59:45.000000000 -0500 +++ new/include/asm-ppc/highmem.h 2003-12-22 16:18:05.000000000 -0500 @@ -81,7 +81,7 @@ unsigned int idx; unsigned long vaddr; - inc_preempt_count(); + preempt_disable(); if (page < highmem_start_page) return page_address(page); @@ -104,7 +104,7 @@ unsigned int idx = type + KM_TYPE_NR*smp_processor_id(); if (vaddr < KMAP_FIX_BEGIN) { // FIXME - dec_preempt_count(); + preempt_disable(); return; } @@ -118,7 +118,7 @@ pte_clear(kmap_pte+idx); flush_tlb_page(0, vaddr); #endif - dec_preempt_count(); + preempt_enable(); } static inline struct page *kmap_atomic_to_page(void *ptr) - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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