On Thu, 30 Jan 2025 18:43:17 +0000 Easwar Hariharan eahariha@linux.microsoft.com wrote:
While converting users of msecs_to_jiffies(), lkp reported that some range checks would always be true because of the mismatch between the implied int value of secs_to_jiffies() vs the unsigned long return value of the msecs_to_jiffies() calls it was replacing. Fix this by casting secs_to_jiffies() values as unsigned long.
Surely 'unsigned long' can't be the right type ? It changes between 32bit and 64bit systems. Either it is allowed to wrap - so should be 32bit on both, or wrapping is unexpected and it needs to be 64bit on both.
As we all know (to our cost in many cases) a ms counter wraps 32bit in about 48 days.
David
Fixes: b35108a51cf7ba ("jiffies: Define secs_to_jiffies()") CC: stable@vger.kernel.org # 6.12+ CC: Andrew Morton akpm@linux-foundation.org Reported-by: kernel test robot lkp@intel.com Closes: https://lore.kernel.org/oe-kbuild-all/202501301334.NB6NszQR-lkp@intel.com/ Signed-off-by: Easwar Hariharan eahariha@linux.microsoft.com
include/linux/jiffies.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/include/linux/jiffies.h b/include/linux/jiffies.h index ed945f42e064..0ea8c9887429 100644 --- a/include/linux/jiffies.h +++ b/include/linux/jiffies.h @@ -537,7 +537,7 @@ static __always_inline unsigned long msecs_to_jiffies(const unsigned int m)
- Return: jiffies value
*/ -#define secs_to_jiffies(_secs) ((_secs) * HZ) +#define secs_to_jiffies(_secs) (unsigned long)((_secs) * HZ) extern unsigned long __usecs_to_jiffies(const unsigned int u); #if !(USEC_PER_SEC % HZ)