diff options
| author | Rusty Russell <rusty@rustcorp.com.au> | 2015-05-09 03:14:13 +0930 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-05-08 07:44:12 +0200 |
| commit | 706470a2092a6478edc7e956c6ba20ec0b547057 (patch) | |
| tree | 64fba7e7cdaeb36965672369bc93b4af6aae1b55 /include | |
| parent | 62011a96b21de60b18b83e2750340f91d369c7e1 (diff) | |
cpumask_set_cpu_local_first => cpumask_local_spread, lament
commit f36963c9d3f6f415732710da3acdd8608a9fa0e5 upstream.
da91309e0a7e (cpumask: Utility function to set n'th cpu...) created a
genuinely weird function. I never saw it before, it went through DaveM.
(He only does this to make us other maintainers feel better about our own
mistakes.)
cpumask_set_cpu_local_first's purpose is say "I need to spread things
across N online cpus, choose the ones on this numa node first"; you call
it in a loop.
It can fail. One of the two callers ignores this, the other aborts and
fails the device open.
It can fail in two ways: allocating the off-stack cpumask, or through a
convoluted codepath which AFAICT can only occur if cpu_online_mask
changes. Which shouldn't happen, because if cpu_online_mask can change
while you call this, it could return a now-offline cpu anyway.
It contains a nonsensical test "!cpumask_of_node(numa_node)". This was
drawn to my attention by Geert, who said this causes a warning on Sparc.
It sets a single bit in a cpumask instead of returning a cpu number,
because that's what the callers want.
It could be made more efficient by passing the previous cpu rather than
an index, but that would be more invasive to the callers.
[backporting for 3.18: only two callers exist, otherwise no change.
The same warning shows up for "!cpumask_of_node()", and I thought
about just addressing the warning, but using the whole fix seemed
better in the end as one of the two callers also lacks the error
handling]
Fixes: da91309e0a7e8966d916a74cce42ed170fde06bf
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (then rebased)
Tested-by: Amir Vadai <amirv@mellanox.com>
Acked-by: Amir Vadai <amirv@mellanox.com>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/cpumask.h | 6 |
1 files changed, 2 insertions, 4 deletions
diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h index 0a9a6da21e74..bb1e42ce626e 100644 --- a/include/linux/cpumask.h +++ b/include/linux/cpumask.h @@ -142,10 +142,8 @@ static inline unsigned int cpumask_any_but(const struct cpumask *mask, return 1; } -static inline int cpumask_set_cpu_local_first(int i, int numa_node, cpumask_t *dstp) +static inline unsigned int cpumask_local_spread(unsigned int i, int node) { - set_bit(0, cpumask_bits(dstp)); - return 0; } @@ -199,7 +197,7 @@ static inline unsigned int cpumask_next_zero(int n, const struct cpumask *srcp) int cpumask_next_and(int n, const struct cpumask *, const struct cpumask *); int cpumask_any_but(const struct cpumask *mask, unsigned int cpu); -int cpumask_set_cpu_local_first(int i, int numa_node, cpumask_t *dstp); +unsigned int cpumask_local_spread(unsigned int i, int node); /** * for_each_cpu - iterate over every cpu in a mask |