Commit 4829c791 authored Jun 14, 2021 by Dennis Zhou

percpu: initialize best_upa variable

Tom reported this finding from clang 10's static analysis [1].

Due to the way the code is written, it will always see a successful loop
iteration. Instead of setting an initial value, check that it was set
instead with BUG_ON() because 0 units per allocation is bogus.

[1] https://lore.kernel.org/lkml/20210515180817.1751084-1-trix@redhat.com/



Reported-by: Tom Rix <trix@redhat.com>
Signed-off-by: Dennis Zhou <dennis@kernel.org>

parent faf65dde

mm/percpu.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -2888,6 +2888,7 @@ static struct pcpu_alloc_info * __init __flatten pcpu_build_alloc_info(
		* Related to atom_size, which could be much larger than the unit_size.
		*/
		last_allocs = INT_MAX;
		best_upa = 0;
		for (upa = max_upa; upa; upa--) {
		int allocs = 0, wasted = 0;

		@@ -2914,6 +2915,7 @@ static struct pcpu_alloc_info * __init __flatten pcpu_build_alloc_info(
		last_allocs = allocs;
		best_upa = upa;
		}
		BUG_ON(!best_upa);
		upa = best_upa;

		/* allocate and fill alloc_info */