diff options
| author | Andrew Howe <ahowe@nvidia.com> | 2010-07-23 20:00:47 +0300 |
|---|---|---|
| committer | Gary King <gking@nvidia.com> | 2010-07-23 20:41:00 -0700 |
| commit | cab2cf99b1e377918629f0b701a438d01f5edefa (patch) | |
| tree | b5303584f0bff24d2ee935922cd6d06ac33c80d0 | |
| parent | 477eedc3c9586ca1ca466d1bbcf3c998e33a3746 (diff) | |
[ARM] Fix race condition 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().
Change-Id: I205a85ebecaedb430860462012d0571b83f08adc
Reviewed-on: http://git-master/r/4342
Reviewed-by: Janne Hellsten <jhellsten@nvidia.com>
Reviewed-by: Gary King <gking@nvidia.com>
Tested-by: Gary King <gking@nvidia.com>
| -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 77b030f5ec09..6c5ccecdbbf3 100644 --- a/arch/arm/mm/highmem.c +++ b/arch/arm/mm/highmem.c @@ -154,19 +154,22 @@ 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)) { |