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| author | Gary King <gking@nvidia.com> | 2010-07-29 17:37:20 +0100 |
|---|---|---|
| committer | Russell King <rmk+kernel@arm.linux.org.uk> | 2010-07-30 23:16:07 +0100 |
| commit | 831e8047eb2af310184a9d4d9e749f3de119ae39 (patch) | |
| tree | f9fd2e3982796a50e2d2b9374c80ba0c1c4204bb /arch | |
| parent | b92b3612134faff171981fad4f0adb33f485e02e (diff) | |
| download | op-kernel-dev-831e8047eb2af310184a9d4d9e749f3de119ae39.zip op-kernel-dev-831e8047eb2af310184a9d4d9e749f3de119ae39.tar.gz | |
ARM: 6279/1: highmem: fix SMP preemption bug in kmap_high_l1_vipt
smp_processor_id() must not be called from a preemptible context (this
is checked by CONFIG_DEBUG_PREEMPT). kmap_high_l1_vipt() was doing so.
This lead to a problem where the wrong per_cpu kmap_high_l1_vipt_depth
could be incremented, causing a BUG_ON(*depth <= 0); in
kunmap_high_l1_vipt().
The solution is to move the call to smp_processor_id() after the call
to preempt_disable().
Originally by: Andrew Howe <ahowe@nvidia.com>
Signed-off-by: Gary King <gking@nvidia.com>
Acked-by: Nicolas Pitre <nico.as.pitre@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/arm/mm/highmem.c | 13 |
1 files changed, 8 insertions, 5 deletions
diff --git a/arch/arm/mm/highmem.c b/arch/arm/mm/highmem.c index 086816b..6ab2440 100644 --- a/arch/arm/mm/highmem.c +++ b/arch/arm/mm/highmem.c @@ -163,19 +163,22 @@ static DEFINE_PER_CPU(int, kmap_high_l1_vipt_depth); void *kmap_high_l1_vipt(struct page *page, pte_t *saved_pte) { - unsigned int idx, cpu = smp_processor_id(); - int *depth = &per_cpu(kmap_high_l1_vipt_depth, cpu); + unsigned int idx, cpu; + int *depth; unsigned long vaddr, flags; pte_t pte, *ptep; + if (!in_interrupt()) + preempt_disable(); + + cpu = smp_processor_id(); + depth = &per_cpu(kmap_high_l1_vipt_depth, cpu); + idx = KM_L1_CACHE + KM_TYPE_NR * cpu; vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx); ptep = TOP_PTE(vaddr); pte = mk_pte(page, kmap_prot); - if (!in_interrupt()) - preempt_disable(); - raw_local_irq_save(flags); (*depth)++; if (pte_val(*ptep) == pte_val(pte)) { |
