Commit 625be345 authored by David Carlier's avatar David Carlier Committed by Tejun Heo
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tools/sched_ext: scx_pair: fix stride == 0 crash on single-CPU systems 



nr_cpu_ids / 2 produces stride 0 on a single-CPU system, which later
causes SCX_BUG_ON(i == j) to fire. Validate stride after option
parsing to also catch invalid user-supplied values via -S.

Signed-off-by: default avatarDavid Carlier <devnexen@gmail.com>
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent 55a24d92

tools/sched_ext/scx_pair.c

+6 −1
Original line number Diff line number Diff line
@@ -56,7 +56,6 @@ int main(int argc, char **argv) 
	skel = SCX_OPS_OPEN(pair_ops, scx_pair);



	skel->rodata->nr_cpu_ids = libbpf_num_possible_cpus();

	assert(skel->rodata->nr_cpu_ids > 0);

	skel->rodata->pair_batch_dur_ns = __COMPAT_ENUM_OR_ZERO("scx_public_consts", "SCX_SLICE_DFL");



	/* pair up the earlier half to the latter by default, override with -s */
@@ -76,6 +75,12 @@ int main(int argc, char **argv) 
		}

	}



	/* Stride must be positive to pair distinct CPUs. */

	if (stride <= 0) {

		fprintf(stderr, "Invalid stride %d, must be positive\n", stride);

		scx_pair__destroy(skel);

		return -1;

	}

	bpf_map__set_max_entries(skel->maps.pair_ctx, skel->rodata->nr_cpu_ids / 2);



	/* Resize arrays so their element count is equal to cpu count. */