CVS commit: src/sys/kern

["Juergen Hannken-Illjes" <hannken%netbsd.org@localhost>]

Module Name:    src
Committed By:   hannken
Date:           Sat Aug  6 11:04:25 UTC 2011

Modified Files:
        src/sys/kern: sys_select.c

Log Message:
Fix the races of direct select()/poll():

- When sel_do_scan() restarts do a full initialization with selclear() so
  we start from an empty set without registered events.  Defer the
  evaluation of l_selret after selclear() and add the count of direct events
  to the count of events.

- For selscan()/pollscan() zero the output descriptors before we poll and
  for selscan() take the sc_lock before we change them.

- Change sel_setevents() to not count events already set.

Reviewed by: YAMAMOTO Takashi <yamt%netbsd.org@localhost>

Should fix PR #44763 (select/poll direct-set optimization seems racy)
       and PR #45187 (select(2) sometimes doesn't wakeup)


To generate a diff of this commit:
cvs rdiff -u -r1.33 -r1.34 src/sys/kern/sys_select.c

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.