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[PATCH 4.9 23/93] gpiolib: skip unwanted events, dont convert them to opposite edge

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4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Bartosz Golaszewski <brgl@bgdev.pl>

commit df1e76f28ffe87d1b065eecab2d0fbb89e6bdee5 upstream.

The previous fix for filtering out of unwatched events was not entirely
correct. Instead of skipping the events we don't want, they are now
interpreted as events with opposing edge.

In order to fix it: always read the GPIO line value on interrupt and
only emit the event if it corresponds with the event type we requested.

Fixes: ad537b822577 ("gpiolib: fix filtering out unwanted events")
Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/gpio/gpiolib.c |    9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -703,24 +703,23 @@ static irqreturn_t lineevent_irq_thread(
 {
 	struct lineevent_state *le = p;
 	struct gpioevent_data ge;
-	int ret;
+	int ret, level;
 
 	ge.timestamp = ktime_get_real_ns();
+	level = gpiod_get_value_cansleep(le->desc);
 
 	if (le->eflags & GPIOEVENT_REQUEST_RISING_EDGE
 	    && le->eflags & GPIOEVENT_REQUEST_FALLING_EDGE) {
-		int level = gpiod_get_value_cansleep(le->desc);
-
 		if (level)
 			/* Emit low-to-high event */
 			ge.id = GPIOEVENT_EVENT_RISING_EDGE;
 		else
 			/* Emit high-to-low event */
 			ge.id = GPIOEVENT_EVENT_FALLING_EDGE;
-	} else if (le->eflags & GPIOEVENT_REQUEST_RISING_EDGE) {
+	} else if (le->eflags & GPIOEVENT_REQUEST_RISING_EDGE && level) {
 		/* Emit low-to-high event */
 		ge.id = GPIOEVENT_EVENT_RISING_EDGE;
-	} else if (le->eflags & GPIOEVENT_REQUEST_FALLING_EDGE) {
+	} else if (le->eflags & GPIOEVENT_REQUEST_FALLING_EDGE && !level) {
 		/* Emit high-to-low event */
 		ge.id = GPIOEVENT_EVENT_FALLING_EDGE;
 	} else {

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[PATCH 4.9 00/93] 4.9.42-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-08-09 20:40 +0200
  [PATCH 4.9 23/93] gpiolib: skip unwanted events, dont convert them to opposite edge Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-08-09 20:40 +0200
  [PATCH 4.9 19/93] timers: Fix overflow in get_next_timer_interrupt Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-08-09 20:40 +0200
  [PATCH 4.9 26/93] ARM: dts: armada-38x: Fix irq type for pca955 Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-08-09 20:40 +0200
  [PATCH 4.9 06/93] iwlwifi: dvm: prevent an out of bounds access Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-08-09 20:40 +0200
  [PATCH 4.9 41/93] ipv4: ipv6: initialize treq->txhash in cookie_v[46]_check() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-08-09 20:40 +0200
  [PATCH 4.9 37/93] tcp_bbr: introduce bbr_bw_to_pacing_rate() helper Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-08-09 20:40 +0200
  [PATCH 4.9 10/93] device property: Make dev_fwnode() public Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-08-09 20:40 +0200
  [PATCH 4.9 40/93] tcp_bbr: init pacing rate on first RTT sample Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-08-09 20:40 +0200
  [PATCH 4.9 11/93] mmc: core: Fix access to HS400-ES devices Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-08-09 20:40 +0200
  [PATCH 4.9 21/93] powerpc/64: Fix __check_irq_replay missing decrementer interrupt Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-08-09 20:40 +0200
  [PATCH 4.9 36/93] tcp_bbr: cut pacing rate only if filled pipe Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-08-09 20:40 +0200
  [PATCH 4.9 12/93] mm, mprotect: flush TLB if potentially racing with a parallel reclaim leaving stale TLB entries Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-08-09 20:40 +0200
  [PATCH 4.9 24/93] ext4: fix SEEK_HOLE/SEEK_DATA for blocksize < pagesize Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-08-09 20:40 +0200
  [PATCH 4.9 20/93] powerpc/tm: Fix saving of TM SPRs in core dump Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-08-09 20:40 +0200
  [PATCH 4.9 33/93] f2fs: sanity check checkpoint segno and blkoff Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-08-09 20:40 +0200
  [PATCH 4.9 29/93] iscsi-target: Fix initial login PDU asynchronous socket close OOPs Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-08-09 20:40 +0200
  [PATCH 4.9 35/93] [media] saa7164: fix double fetch PCIe access condition Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-08-09 20:40 +0200
  [PATCH 4.9 32/93] media: lirc: LIRC_GET_REC_RESOLUTION should return microseconds Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-08-09 20:40 +0200
  [PATCH 4.9 01/93] parisc: Handle vmas whose context is not current in flush_cache_range Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-08-09 20:40 +0200
  [PATCH 4.9 44/93] net: dsa: b53: Add missing ARL entries for BCM53125 Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-08-09 20:40 +0200
  [PATCH 4.9 08/93] NFSv4: Fix EXCHANGE_ID corrupt verifier issue Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-08-09 20:40 +0200
  [PATCH 4.9 43/93] ipv6: avoid overflow of offset in ip6_find_1stfragopt Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-08-09 20:40 +0200
  Re: [PATCH 4.9 00/93] 4.9.42-stable review Shuah Khan <shuahkh@osg.samsung.com> - 2017-08-10 02:20 +0200
  Re: [PATCH 4.9 00/93] 4.9.42-stable review Guenter Roeck <linux@roeck-us.net> - 2017-08-10 02:50 +0200
  Re: [PATCH 4.9 00/93] 4.9.42-stable review Sumit Semwal <sumit.semwal@linaro.org> - 2017-08-10 05:10 +0200

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