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| author |   Paul E. McKenney <paulmck@kernel.org> | 2020-08-27 09:58:19 -0700 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@kernel.org> | 2020-11-02 17:13:29 -0800 |
| commit | 0c6d18d84db11840dd0f3f65750c6ea0bb6b8e0d (patch) | |
| tree | a909c61492a1834bcae501fce1abe448e3975d2c /kernel/rcu/refscale.c | |
| parent | Linux 5.10-rc1 (diff) | |
| download | linux-dev-0c6d18d84db11840dd0f3f65750c6ea0bb6b8e0d.tar.xz linux-dev-0c6d18d84db11840dd0f3f65750c6ea0bb6b8e0d.zip | |
refscale: Bounds-check module parameters
The default value for refscale.nreaders is -1, which results in the code
setting the value to three-quarters of the number of CPUs. On single-CPU
systems, this results in three-quarters of the value one, which the C
language's integer arithmetic rounds to zero. This in turn results in
a divide-by-zero error.
This commit therefore adds bounds checking to the refscale module
parameters, so that if they are less than one, they are set to the
value one.
Reported-by: kernel test robot <lkp@intel.com>
Tested-by "Chen, Rong A" <rong.a.chen@intel.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Diffstat (limited to '')
| -rw-r--r-- | kernel/rcu/refscale.c | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/kernel/rcu/refscale.c b/kernel/rcu/refscale.c index 952595c678b3..fb5f20d9486a 100644 --- a/kernel/rcu/refscale.c +++ b/kernel/rcu/refscale.c @@ -681,6 +681,12 @@ ref_scale_init(void) // Reader tasks (default to ~75% of online CPUs). if (nreaders < 0) nreaders = (num_online_cpus() >> 1) + (num_online_cpus() >> 2); + if (WARN_ONCE(loops <= 0, "%s: loops = %ld, adjusted to 1\n", __func__, loops)) + loops = 1; + if (WARN_ONCE(nreaders <= 0, "%s: nreaders = %d, adjusted to 1\n", __func__, nreaders)) + nreaders = 1; + if (WARN_ONCE(nruns <= 0, "%s: nruns = %d, adjusted to 1\n", __func__, nruns)) + nruns = 1; reader_tasks = kcalloc(nreaders, sizeof(reader_tasks[0]), GFP_KERNEL); if (!reader_tasks) { |