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Document where in scan_task the scan state can change, and potentially

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deal/log a warning if the scan flags change during one of those race
windows.

It's highly likely that I need to actually sit down and replace this
scan infrastructure at some point.  It has some other side effects too -
the scan task is a blocking task scheduled in the net80211 taskqueue;
so drivers that use this taskqueue have other things not run.  Eek.

If you see this printf happen then please let me know!
This commit is contained in:
Adrian Chadd 2014-12-20 19:41:31 +00:00
parent b9450e431d
commit 92c59ab94f
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=275964
1 changed files with 21 additions and 2 deletions
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23
sys/net80211/ieee80211_scan.c
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@ -882,6 +882,9 @@ scan_task(void *arg, int pending)
}
scanend = ticks + SCAN_PRIVATE(ss)->ss_duration;
/* XXX scan state can change! Re-validate scan state! */
IEEE80211_UNLOCK(ic);
ic->ic_scan_start(ic); /* notify driver */
IEEE80211_LOCK(ic);
@ -944,6 +947,8 @@ scan_task(void *arg, int pending)
ic->ic_scan_curchan(ss, maxdwell);
IEEE80211_LOCK(ic);
/* XXX scan state can change! Re-validate scan state! */
SCAN_PRIVATE(ss)->ss_chanmindwell = ticks + ss->ss_mindwell;
/* clear mindwell lock and initial channel change flush */
SCAN_PRIVATE(ss)->ss_iflags &= ~ISCAN_REP;
@ -960,6 +965,7 @@ scan_task(void *arg, int pending)
IEEE80211_UNLOCK(ic);
ic->ic_scan_end(ic); /* notify driver */
IEEE80211_LOCK(ic);
/* XXX scan state can change! Re-validate scan state! */
/*
* Since a cancellation may have occured during one of the
@ -969,10 +975,10 @@ scan_task(void *arg, int pending)
((SCAN_PRIVATE(ss)->ss_iflags & ISCAN_CANCEL) != 0)) {
/* XXX printf? */
if_printf(vap->iv_ifp,
"%s: OOPS! scan cancelled during driver call!\n",
"%s: OOPS! scan cancelled during driver call (1)!\n",
__func__);
scandone = 1;
}
scandone |= ((SCAN_PRIVATE(ss)->ss_iflags & ISCAN_CANCEL) != 0);
/*
* Record scan complete time. Note that we also do
@ -1031,6 +1037,19 @@ scan_task(void *arg, int pending)
__func__, scandone ? "done" : "stopped",
ticks, ss->ss_mindwell, scanend);
/*
* Since a cancellation may have occured during one of the
* driver calls (whilst unlocked), update scandone.
*/
if (scandone == 0 &&
((SCAN_PRIVATE(ss)->ss_iflags & ISCAN_CANCEL) != 0)) {
/* XXX printf? */
if_printf(vap->iv_ifp,
"%s: OOPS! scan cancelled during driver call (2)!\n",
__func__);
scandone = 1;
}
/*
* Clear the SCAN bit first in case frames are
* pending on the station power save queue. If