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| author | Ira Weiny <ira.weiny@intel.com> | 2020-10-13 16:52:33 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2020-10-13 18:38:30 -0700 |
| commit | 433e7d3177544c8cf0b6375abd310b0ef023fe9d (patch) | |
| tree | 3afd4553d29a14577a9caa53caaca2b78de85156 /mm/memremap.c | |
| parent | 822bca52ee7eb279acfba261a423ed7ac47d6f73 (diff) | |
| download | lwn-433e7d3177544c8cf0b6375abd310b0ef023fe9d.tar.gz lwn-433e7d3177544c8cf0b6375abd310b0ef023fe9d.zip | |
mm/memremap.c: convert devmap static branch to {inc,dec}
While reviewing Protection Key Supervisor support it was pointed out that
using a counter to track static branch enable was an anti-pattern which
was better solved using the provided static_branch_{inc,dec} functions.[1]
Fix up devmap_managed_key to work the same way. Also this should be safer
because there is a very small (very unlikely) race when multiple callers
try to enable at the same time.
[1] https://lore.kernel.org/lkml/20200714194031.GI5523@worktop.programming.kicks-ass.net/
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Vishal Verma <vishal.l.verma@intel.com>
Link: https://lkml.kernel.org/r/20200810235319.2796597-1-ira.weiny@intel.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/memremap.c')
| -rw-r--r-- | mm/memremap.c | 7 |
1 files changed, 2 insertions, 5 deletions
diff --git a/mm/memremap.c b/mm/memremap.c index 7dc7aec971de..198083453182 100644 --- a/mm/memremap.c +++ b/mm/memremap.c @@ -40,12 +40,10 @@ EXPORT_SYMBOL_GPL(memremap_compat_align); #ifdef CONFIG_DEV_PAGEMAP_OPS DEFINE_STATIC_KEY_FALSE(devmap_managed_key); EXPORT_SYMBOL(devmap_managed_key); -static atomic_t devmap_managed_enable; static void devmap_managed_enable_put(void) { - if (atomic_dec_and_test(&devmap_managed_enable)) - static_branch_disable(&devmap_managed_key); + static_branch_dec(&devmap_managed_key); } static int devmap_managed_enable_get(struct dev_pagemap *pgmap) @@ -56,8 +54,7 @@ static int devmap_managed_enable_get(struct dev_pagemap *pgmap) return -EINVAL; } - if (atomic_inc_return(&devmap_managed_enable) == 1) - static_branch_enable(&devmap_managed_key); + static_branch_inc(&devmap_managed_key); return 0; } #else |