Messages in this thread Patch in this message |  | | From | Zheng Yejian <> | Subject | [PATCH 1/2] acct: Fix accuracy loss for input value of encode_comp_t() | Date | Sat, 15 May 2021 22:06:30 +0800 |
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See calculation of ac_{u,s}time in fill_ac(): > ac->ac_utime = encode_comp_t(nsec_to_AHZ(pacct->ac_utime)); > ac->ac_stime = encode_comp_t(nsec_to_AHZ(pacct->ac_stime));
Return value of nsec_to_AHZ() is always type of 'u64', but it is handled as type of 'unsigned long' in encode_comp_t, and accuracy loss would happen on 32-bit platform when 'unsigned long' value is 32-bit-width.
So 'u64' value of encode_comp_t() may look better.
Signed-off-by: Zheng Yejian <zhengyejian1@huawei.com> --- kernel/acct.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/kernel/acct.c b/kernel/acct.c index a64102be2bb0..9e143ed5b5d0 100644 --- a/kernel/acct.c +++ b/kernel/acct.c @@ -301,7 +301,7 @@ void acct_exit_ns(struct pid_namespace *ns) } /* - * encode an unsigned long into a comp_t + * encode an u64 into a comp_t * * This routine has been adopted from the encode_comp_t() function in * the kern_acct.c file of the FreeBSD operating system. The encoding @@ -312,7 +312,7 @@ void acct_exit_ns(struct pid_namespace *ns) #define EXPSIZE 3 /* Base 8 (3 bit) exponent. */ #define MAXFRACT ((1 << MANTSIZE) - 1) /* Maximum fractional value. */ -static comp_t encode_comp_t(unsigned long value) +static comp_t encode_comp_t(u64 value) { int exp, rnd; -- 2.17.1
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