diff options
author | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-08-14 23:35:22 +0300 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-08-14 23:35:22 +0300 |
commit | 8652892ed44914edfb488c280ccf79301fd89117 (patch) | |
tree | 16b49cb72d4962742855ae639a82c393cbf4c158 /include/linux/cpuset.h | |
parent | 5551ad1e9fad2cf06288c6e93cb95f879b8cdf5e (diff) | |
parent | ef954844c7ace62f773f4f23e28d2d915adc419f (diff) | |
download | linux-8652892ed44914edfb488c280ccf79301fd89117.tar.xz |
Merge 4.13-rc5 into staging-next
We need it here for iio fixes.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'include/linux/cpuset.h')
-rw-r--r-- | include/linux/cpuset.h | 19 |
1 files changed, 17 insertions, 2 deletions
diff --git a/include/linux/cpuset.h b/include/linux/cpuset.h index 119a3f9604b0..898cfe2eeb42 100644 --- a/include/linux/cpuset.h +++ b/include/linux/cpuset.h @@ -18,6 +18,19 @@ #ifdef CONFIG_CPUSETS +/* + * Static branch rewrites can happen in an arbitrary order for a given + * key. In code paths where we need to loop with read_mems_allowed_begin() and + * read_mems_allowed_retry() to get a consistent view of mems_allowed, we need + * to ensure that begin() always gets rewritten before retry() in the + * disabled -> enabled transition. If not, then if local irqs are disabled + * around the loop, we can deadlock since retry() would always be + * comparing the latest value of the mems_allowed seqcount against 0 as + * begin() still would see cpusets_enabled() as false. The enabled -> disabled + * transition should happen in reverse order for the same reasons (want to stop + * looking at real value of mems_allowed.sequence in retry() first). + */ +extern struct static_key_false cpusets_pre_enable_key; extern struct static_key_false cpusets_enabled_key; static inline bool cpusets_enabled(void) { @@ -32,12 +45,14 @@ static inline int nr_cpusets(void) static inline void cpuset_inc(void) { + static_branch_inc(&cpusets_pre_enable_key); static_branch_inc(&cpusets_enabled_key); } static inline void cpuset_dec(void) { static_branch_dec(&cpusets_enabled_key); + static_branch_dec(&cpusets_pre_enable_key); } extern int cpuset_init(void); @@ -115,7 +130,7 @@ extern void cpuset_print_current_mems_allowed(void); */ static inline unsigned int read_mems_allowed_begin(void) { - if (!cpusets_enabled()) + if (!static_branch_unlikely(&cpusets_pre_enable_key)) return 0; return read_seqcount_begin(¤t->mems_allowed_seq); @@ -129,7 +144,7 @@ static inline unsigned int read_mems_allowed_begin(void) */ static inline bool read_mems_allowed_retry(unsigned int seq) { - if (!cpusets_enabled()) + if (!static_branch_unlikely(&cpusets_enabled_key)) return false; return read_seqcount_retry(¤t->mems_allowed_seq, seq); |