Messages in this thread | | | From | Maciej Żenczykowski <> | Date | Sat, 28 Mar 2020 09:56:58 -0700 | Subject | Re: [RFC PATCH v1 18/50] net/ipv6/addrconf.c: Use prandom_u32_max for rfc3315 backoff time computation |
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> /* multiply 'initial retransmission time' by 0.9 .. 1.1 */ > - u64 tmp = (900000 + prandom_u32() % 200001) * (u64)irt; > - do_div(tmp, 1000000); > - return (s32)tmp; > + s32 range = irt / 5; > + return irt - (s32)(range/2) + (s32)prandom_u32_max(range);
The cast on range/2 looks entirely spurious
> /* multiply 'retransmission timeout' by 1.9 .. 2.1 */ > - u64 tmp = (1900000 + prandom_u32() % 200001) * (u64)rt; > - do_div(tmp, 1000000); > - if ((s32)tmp > mrt) { > + s32 range = rt / 5; > + s32 tmp = 2*rt - (s32)(range/2) + (s32)prandom_u32_max(range);
Here as well. Honestly the cast on prandom might also not be necessary, but that at least has a reason.
> + if (tmp > mrt) { > /* multiply 'maximum retransmission time' by 0.9 .. 1.1 */ > - tmp = (900000 + prandom_u32() % 200001) * (u64)mrt; > - do_div(tmp, 1000000); > + range = mrt / 5; > + tmp = mrt - (s32)(range/2) + (s32)prandom_u32_max(range);
Ditto.
> } > return (s32)tmp; > }
- Maciej
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