From 8ec6a8ec23b9529d6203cab50a22fab3a5fd0d80 Mon Sep 17 00:00:00 2001 From: Takashi Sakamoto Date: Wed, 24 Sep 2025 22:11:40 +0900 Subject: [PATCH] firewire: core: suppress overflow warning when computing jiffies from isochronous cycle The multiplication by USEC_PER_SEC (=1000000L) may trigger an overflow warning with 32 bit storage. In the case of the subsystem the input value ranges between 800 and 16000, thus the result always fits within 32 bit storage. This commit suppresses the warning by using widening conversion to 64 bit storage before multiplication, then using narrowing conversion to 32 bit storage. Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-kbuild-all/202509170136.b5ZHaNAV-lkp@intel.com/ Fixes: 379b870c28c6 ("firewire: core: use helper macros instead of direct access to HZ") Link: https://lore.kernel.org/r/20250924131140.261686-1-o-takashi@sakamocchi.jp Signed-off-by: Takashi Sakamoto --- drivers/firewire/core.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/firewire/core.h b/drivers/firewire/core.h index 7f2ca93406ce..2dd715a580ac 100644 --- a/drivers/firewire/core.h +++ b/drivers/firewire/core.h @@ -30,7 +30,7 @@ struct fw_packet; // This is the arbitrary value we use to indicate a mismatched gap count. #define GAP_COUNT_MISMATCHED 0 -#define isoc_cycles_to_jiffies(cycles) usecs_to_jiffies(cycles * USEC_PER_SEC / 8000) +#define isoc_cycles_to_jiffies(cycles) usecs_to_jiffies((u32)((u64)(cycles) * USEC_PER_SEC / 8000)) extern __printf(2, 3) void fw_err(const struct fw_card *card, const char *fmt, ...); -- 2.20.1