Date: Fri, 2 Mar 2012 02:53:44 +0000 (UTC) From: Adrian Chadd <adrian@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r232373 - head/sys/net80211 Message-ID: <201203020253.q222riIG010124@svn.freebsd.org>
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Author: adrian Date: Fri Mar 2 02:53:43 2012 New Revision: 232373 URL: http://svn.freebsd.org/changeset/base/232373 Log: Attempt to catch scan cancellations at exactly the wrong time from occuring. The scan code unlocks the comlock and calls into the driver. It then assumes the state hasn't changed from underneath it. Although I haven't seen this particular condition trigger, I'd like to be informed if I or anyone else sees it. What I'm thinking may occur: * A cancellation comes in during the scan_end call; * the cancel flag is set; * but it's never checked, so scandone isn't updated; * .. and the interface stays in the STA power save mode. It's a subtle race, if it even exists. PR: kern/163318 Modified: head/sys/net80211/ieee80211_scan.c Modified: head/sys/net80211/ieee80211_scan.c ============================================================================== --- head/sys/net80211/ieee80211_scan.c Fri Mar 2 00:21:07 2012 (r232372) +++ head/sys/net80211/ieee80211_scan.c Fri Mar 2 02:53:43 2012 (r232373) @@ -960,6 +960,19 @@ scan_task(void *arg, int pending) IEEE80211_LOCK(ic); /* + * 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!\n", + __func__); + } + scandone |= ((SCAN_PRIVATE(ss)->ss_iflags & ISCAN_CANCEL) != 0); + + /* * Record scan complete time. Note that we also do * this when canceled so any background scan will * not be restarted for a while.
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