mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-09-12 13:55:32 +00:00
![]() This simplifies the calculation of a value p for a given fval when the first loss interval is computed (RFC 3448, 6.3.1). It makes use of the two new functions scaled_div/scaled_div32 to provide overflow protection. Additionally, protection against divide-by-zero is extended - in this case the function will return the maximally possible value of p=100%. Background: The maximum fval, f(100%), is approximately 244, i.e. the scaled value of fval should never exceed 244E6, which fits easily into u32. The problem is the scaling by 10^6, since additionally R(TT) is in microseconds. This is resolved by breaking the division into two stages: the first stage computes fval=(s*10^6)/R, stores that into u64; the second stage computes fval = (fval*10^6)/X_recv and complains if overflow is reached for u32. This case is safe since the TFRC reverse-lookup routine then returns p=100%. Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk> Acked-by: Ian McDonald <ian.mcdonald@jandi.co.nz> Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com> |
||
---|---|---|
.. | ||
lib | ||
ccid2.c | ||
ccid2.h | ||
ccid3.c | ||
ccid3.h | ||
Kconfig | ||
Makefile |