d/freebsd-dev
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Change several constants used by the PIE algorithm from unsigned to signed.

Browse Source 
- PIE_MAX_PROB is compared to variable of int64_t and the type promotion
   rules can cause the value of that variable to be treated as unsigned.
   If the value is actually negative, then the result of the comparsion
   is incorrect, causing the algorithm to perform poorly in some
   situations.  Changing the constant to be signed cause the comparision
   to work correctly.

 - PIE_SCALE is also compared to signed values.  Fortunately they are
   also compared to zero and negative values are discarded so this is
   more of a cosmetic fix.

 - PIE_DQ_THRESHOLD is only compared to unsigned values, but it is small
   enough that the automatic promotion to unsigned is harmless.

Submitted by:	Rasool Al-Saadi <ralsaadi@swin.edu.au>
MFC after:	1 week
This commit is contained in:
Don Lewis 2017-03-18 23:00:13 +00:00
parent 0620d81993
commit 46c8aadb6f
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=315516
1 changed files with 3 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
sys/netpfil/ipfw/dn_aqm_pie.h
View File

@ -37,16 +37,16 @@
#define DN_AQM_PIE 2
#define PIE_DQ_THRESHOLD_BITS 14
/* 2^14 =16KB */
#define PIE_DQ_THRESHOLD (1UL << PIE_DQ_THRESHOLD_BITS)
#define PIE_DQ_THRESHOLD (1L << PIE_DQ_THRESHOLD_BITS)
#define MEAN_PKTSIZE 800
/* 31-bits because random() generates range from 0->(2**31)-1 */
#define PIE_PROB_BITS 31
#define PIE_MAX_PROB ((1ULL<<PIE_PROB_BITS) -1)
#define PIE_MAX_PROB ((1LL<<PIE_PROB_BITS) -1)
/* for 16-bits, we have 3-bits for integer part and 13-bits for fraction */
#define PIE_FIX_POINT_BITS 13
#define PIE_SCALE (1UL<<PIE_FIX_POINT_BITS)
#define PIE_SCALE (1L<<PIE_FIX_POINT_BITS)
/* PIE options */