| Message ID | 20200810235319.2796597-1-ira.weiny@intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | memremap: Convert devmap static branch to {inc,dec} | expand |
Looks good to me. Reviewed-by: William Kucharski <william.kucharski@oracle.com> > On Aug 10, 2020, at 5:53 PM, ira.weiny@intel.com wrote: > > From: Ira Weiny <ira.weiny@intel.com> > > 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/ > > Cc: Dan Williams <dan.j.williams@intel.com> > Cc: Vishal Verma <vishal.l.verma@intel.com> > Signed-off-by: Ira Weiny <ira.weiny@intel.com> > --- > mm/memremap.c | 7 ++----- > 1 file changed, 2 insertions(+), 5 deletions(-) > > diff --git a/mm/memremap.c b/mm/memremap.c > index 03e38b7a38f1..9fb9ad500e78 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 > -- > 2.28.0.rc0.12.gb6a658bd00c9 > >
diff --git a/mm/memremap.c b/mm/memremap.c index 03e38b7a38f1..9fb9ad500e78 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