From 5eefe17c7ae41bac4d2d281669e8357a10f4d5a4 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Tue, 10 May 2022 11:51:59 -0700 Subject: [PATCH] libbpf: Clean up ringbuf size adjustment implementation Drop unused iteration variable, move overflow prevention check into the for loop. Fixes: 0087a681fa8c ("libbpf: Automatically fix up BPF_MAP_TYPE_RINGBUF size, if necessary") Reported-by: Nathan Chancellor Signed-off-by: Andrii Nakryiko Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/bpf/20220510185159.754299-1-andrii@kernel.org --- tools/lib/bpf/libbpf.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index a5904c0..0e74fae 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -4951,7 +4951,7 @@ static bool is_pow_of_2(size_t x) static size_t adjust_ringbuf_sz(size_t sz) { __u32 page_sz = sysconf(_SC_PAGE_SIZE); - __u32 i, mul; + __u32 mul; /* if user forgot to set any size, make sure they see error */ if (sz == 0) @@ -4967,9 +4967,7 @@ static size_t adjust_ringbuf_sz(size_t sz) * user-set size to satisfy both user size request and kernel * requirements and substitute correct max_entries for map creation. */ - for (i = 0, mul = 1; ; i++, mul <<= 1) { - if (mul > UINT_MAX / page_sz) /* prevent __u32 overflow */ - break; + for (mul = 1; mul <= UINT_MAX / page_sz; mul <<= 1) { if (mul * page_sz > sz) return mul * page_sz; } -- 2.7.4