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[net80211] Fix interrupted scan logic and ticks comparison

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The scan task refactoring stuff circa 2014-2016 broke the blocking task
 into a taskqueue with some async bits, but it apparently broke scans
 being interrupted by traffic.

Notably - the new "field" SCAN_PAUSE sets both SCAN_INTERRUPT and SCAN_CANCEL,
and a bunch of existing code was checking for SCAN_CANCEL only and breaking
the scan. Unfortunately it was then (a) cancelling the scan entirely and
(b) not notifying userland that scan was done.

So:
* Update the calls to scan_end() to only pass in 1 (saying the scan is complete)
  if SCAN_CANCEL is set WITHOUT SCAN_INTERRUPT. If both are set then yes,
  the scan is interrupted, but it isn't canceled - it's just paused.
* Update the "did the scan flags change whilst the driver was called" logic
  to check for canceled scans, not interrupted scans.
* The "scan done" logic now explicitly checks for either interrupted or
  completed scans. This accounts for the situation where a scan is being
  aborted via traffic but it ALSO happens to have finished (ie the last
  channel was checked.)

This doesn't ENTIRELY fix scanning as the resume function is broken
due to incorrect ticks math. Thus, the second half of this patch
changes the ieee80211_ticks_*() macros to use int instead of long,
matching the logic that the TCP code does with ticks and handles
wrapping / negative ticks values. If cast to long then the wrapping
math wouldn't work right (ie, if ticks was actually negative,
ie, after the system has been up for a while.)

This allows contbgscan() to correctly calculate if a scan should
continue based on ticks and ic->ic_lastdata .

Reviewed by:	bz
Differential Revision:	https://reviews.freebsd.org/D25031
This commit is contained in:
Adrian Chadd 2020-05-27 18:32:12 +00:00
parent 1add7d0f8d
commit 67a26c98f2
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=361560
2 changed files with 37 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
sys/net80211/ieee80211_freebsd.h
View File

@ -254,9 +254,9 @@ void ieee80211_vap_destroy(struct ieee80211vap *);
#define ticks_to_msecs(t) TICKS_2_MSEC(t)
#define ticks_to_secs(t) ((t) / hz)
#define ieee80211_time_after(a,b) ((long)(b) - (long)(a) < 0)
#define ieee80211_time_after(a,b) ((int)(b) - (int)(a) < 0)
#define ieee80211_time_before(a,b) ieee80211_time_after(b,a)
#define ieee80211_time_after_eq(a,b) ((long)(a) - (long)(b) >= 0)
#define ieee80211_time_after_eq(a,b) ((int)(a) - (int)(b) >= 0)
#define ieee80211_time_before_eq(a,b) ieee80211_time_after_eq(b,a)
struct mbuf *ieee80211_getmgtframe(uint8_t **frm, int headroom, int pktlen);

48
sys/net80211/ieee80211_scan_sw.c
View File

@ -675,19 +675,32 @@ scan_curchan_task(void *arg, int pending)
struct ieee80211com *ic = ss->ss_ic;
struct ieee80211_channel *chan;
unsigned long maxdwell;
int scandone;
int scandone, scanstop;
IEEE80211_LOCK(ic);
end:
/*
* Note: only /end/ the scan if we're CANCEL rather than
* CANCEL+INTERRUPT (ie, 'PAUSE').
*
* We can stop the scan if we hit cancel, but we shouldn't
* call scan_end(ss, 1) if we're just PAUSEing the scan.
*/
scandone = (ss->ss_next >= ss->ss_last) ||
(ss_priv->ss_iflags & ISCAN_CANCEL) != 0;
((ss_priv->ss_iflags & ISCAN_PAUSE) == ISCAN_CANCEL);
scanstop = (ss->ss_next >= ss->ss_last) ||
((ss_priv->ss_iflags & ISCAN_CANCEL) != 0);
IEEE80211_DPRINTF(ss->ss_vap, IEEE80211_MSG_SCAN,
"%s: loop start; scandone=%d\n",
"%s: loop start; scandone=%d, scanstop=%d, ss_iflags=0x%x, ss_next=%u, ss_last=%u\n",
__func__,
scandone);
scandone,
scanstop,
(uint32_t) ss_priv->ss_iflags,
(uint32_t) ss->ss_next,
(uint32_t) ss->ss_last);
if (scandone || (ss->ss_flags & IEEE80211_SCAN_GOTPICK) ||
if (scanstop || (ss->ss_flags & IEEE80211_SCAN_GOTPICK) ||
(ss_priv->ss_iflags & ISCAN_ABORT) ||
ieee80211_time_after(ticks + ss->ss_mindwell, ss_priv->ss_scanend)) {
ss_priv->ss_iflags &= ~ISCAN_RUNNING;
@ -787,11 +800,12 @@ scan_end(struct ieee80211_scan_state *ss, int scandone)
* Since a cancellation may have occurred during one of the
* driver calls (whilst unlocked), update scandone.
*/
if (scandone == 0 && (ss_priv->ss_iflags & ISCAN_CANCEL) != 0) {
if ((scandone == 0) && ((ss_priv->ss_iflags & ISCAN_PAUSE) == ISCAN_CANCEL)) {
/* XXX printf? */
if_printf(vap->iv_ifp,
"%s: OOPS! scan cancelled during driver call (1)!\n",
__func__);
"%s: OOPS! scan cancelled during driver call (1) (ss_iflags=0x%x)!\n",
__func__,
ss_priv->ss_iflags);
scandone = 1;
}
@ -856,11 +870,12 @@ scan_end(struct ieee80211_scan_state *ss, int scandone)
* Since a cancellation may have occurred during one of the
* driver calls (whilst unlocked), update scandone.
*/
if (scandone == 0 && (ss_priv->ss_iflags & ISCAN_CANCEL) != 0) {
if (scandone == 0 && (ss_priv->ss_iflags & ISCAN_PAUSE) == ISCAN_CANCEL) {
/* XXX printf? */
if_printf(vap->iv_ifp,
"%s: OOPS! scan cancelled during driver call (2)!\n",
__func__);
"%s: OOPS! scan cancelled during driver call (2) (ss_iflags=0x%x)!\n",
__func__,
ss_priv->ss_iflags);
scandone = 1;
}
@ -900,11 +915,18 @@ scan_done(struct ieee80211_scan_state *ss, int scandone)
*/
if ((vap->iv_flags_ext & IEEE80211_FEXT_SCAN_OFFLOAD) == 0)
vap->iv_sta_ps(vap, 0);
if (ss->ss_next >= ss->ss_last)
if (ss->ss_next >= ss->ss_last) {
IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
"%s: Dropping out of scan; ss_next=%u, ss_last=%u\n",
__func__,
(uint32_t) ss->ss_next,
(uint32_t) ss->ss_last);
ic->ic_flags_ext &= ~IEEE80211_FEXT_BGSCAN;
}
/* send 'scan done' event if not interrupted due to traffic. */
if (!(ss_priv->ss_iflags & ISCAN_INTERRUPT))
if (!(ss_priv->ss_iflags & ISCAN_INTERRUPT) ||
(ss->ss_next >= ss->ss_last))
ieee80211_notify_scan_done(vap);
}
ss_priv->ss_iflags &= ~(ISCAN_PAUSE | ISCAN_ABORT);