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| author | Rusty Russell <rusty@rustcorp.com.au> | 2009-01-01 10:12:30 +1030 |
|---|---|---|
| committer | Rusty Russell <rusty@rustcorp.com.au> | 2009-01-01 10:12:30 +1030 |
| commit | 2a53008033189ed09bfe241c6b33811ba4ce980d (patch) | |
| tree | 86dcdacdd7fbaf671f2487b7a05352aa672fecc1 /lib/cpumask.c | |
| parent | 5db0e1e9e0f30f160b832a0b5cd1131954bf4f6e (diff) | |
| download | lwn-2a53008033189ed09bfe241c6b33811ba4ce980d.tar.gz lwn-2a53008033189ed09bfe241c6b33811ba4ce980d.zip | |
cpumask: zero extra bits in alloc_cpumask_var_node
Impact: extra safety checks during transition
When CONFIG_CPUMASKS_OFFSTACK is set, the new cpumask_ operators only
use bits up to nr_cpu_ids, not NR_CPUS. Using the old cpus_ operators
on these masks can mean accessing undefined bits.
After some discussion, Mike and I decided to err on the side of caution;
we zero the "undefined" bits in alloc_cpumask_var_node() until all the
old cpumask functions are removed.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Diffstat (limited to 'lib/cpumask.c')
| -rw-r--r-- | lib/cpumask.c | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/lib/cpumask.c b/lib/cpumask.c index 8e1496cb63f7..3389e2440da0 100644 --- a/lib/cpumask.c +++ b/lib/cpumask.c @@ -107,6 +107,14 @@ bool alloc_cpumask_var_node(cpumask_var_t *mask, gfp_t flags, int node) dump_stack(); } #endif + /* FIXME: Bandaid to save us from old primitives which go to NR_CPUS. */ + if (*mask) { + unsigned int tail; + tail = BITS_TO_LONGS(NR_CPUS - nr_cpumask_bits) * sizeof(long); + memset(cpumask_bits(*mask) + cpumask_size() - tail, + 0, tail); + } + return *mask != NULL; } EXPORT_SYMBOL(alloc_cpumask_var_node); |