linux-kernel - [ 102/262] mISDN: Fix wrong usage of flush_work

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Message-Id: <20120928183010.168233564@linuxfoundation.org>
Date:	Fri, 28 Sep 2012 11:50:31 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:	Greg KH <gregkh@...uxfoundation.org>, alan@...rguk.ukuu.org.uk,
	Karsten Keil <keil@...systems.de>,
	"David S. Miller" <davem@...emloft.net>
Subject: [ 102/262] mISDN: Fix wrong usage of flush_work_sync while holding locks

From: Greg KH <gregkh@...uxfoundation.org>

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

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

From: Karsten Keil <keil@...systems.de>

commit 4b921eda53366b319602351ff4d7256fafa4bd1b upstream.

It is a bad idea to hold a spinlock and call flush_work_sync.
Move the workqueue cleanup outside the spinlock and use cancel_work_sync,
on closing the channel this seems to be the more correct function.
Remove the never used and constant return value of mISDN_freebchannel.

Signed-off-by: Karsten Keil <keil@...systems.de>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/isdn/hardware/mISDN/avmfritz.c  |    3 ++-
 drivers/isdn/hardware/mISDN/mISDNipac.c |    3 ++-
 drivers/isdn/hardware/mISDN/mISDNisar.c |    3 ++-
 drivers/isdn/hardware/mISDN/netjet.c    |    3 ++-
 drivers/isdn/hardware/mISDN/w6692.c     |    3 ++-
 drivers/isdn/mISDN/hwchannel.c          |    9 ++++-----
 include/linux/mISDNhw.h                 |    2 +-
 7 files changed, 15 insertions(+), 11 deletions(-)

--- a/drivers/isdn/hardware/mISDN/avmfritz.c
+++ b/drivers/isdn/hardware/mISDN/avmfritz.c
@@ -857,8 +857,9 @@ avm_bctrl(struct mISDNchannel *ch, u32 c
 	switch (cmd) {
 	case CLOSE_CHANNEL:
 		test_and_clear_bit(FLG_OPEN, &bch->Flags);
+		cancel_work_sync(&bch->workq);
 		spin_lock_irqsave(&fc->lock, flags);
-		mISDN_freebchannel(bch);
+		mISDN_clear_bchannel(bch);
 		modehdlc(bch, ISDN_P_NONE);
 		spin_unlock_irqrestore(&fc->lock, flags);
 		ch->protocol = ISDN_P_NONE;
--- a/drivers/isdn/hardware/mISDN/mISDNipac.c
+++ b/drivers/isdn/hardware/mISDN/mISDNipac.c
@@ -1406,8 +1406,9 @@ hscx_bctrl(struct mISDNchannel *ch, u32
 	switch (cmd) {
 	case CLOSE_CHANNEL:
 		test_and_clear_bit(FLG_OPEN, &bch->Flags);
+		cancel_work_sync(&bch->workq);
 		spin_lock_irqsave(hx->ip->hwlock, flags);
-		mISDN_freebchannel(bch);
+		mISDN_clear_bchannel(bch);
 		hscx_mode(hx, ISDN_P_NONE);
 		spin_unlock_irqrestore(hx->ip->hwlock, flags);
 		ch->protocol = ISDN_P_NONE;
--- a/drivers/isdn/hardware/mISDN/mISDNisar.c
+++ b/drivers/isdn/hardware/mISDN/mISDNisar.c
@@ -1588,8 +1588,9 @@ isar_bctrl(struct mISDNchannel *ch, u32
 	switch (cmd) {
 	case CLOSE_CHANNEL:
 		test_and_clear_bit(FLG_OPEN, &bch->Flags);
+		cancel_work_sync(&bch->workq);
 		spin_lock_irqsave(ich->is->hwlock, flags);
-		mISDN_freebchannel(bch);
+		mISDN_clear_bchannel(bch);
 		modeisar(ich, ISDN_P_NONE);
 		spin_unlock_irqrestore(ich->is->hwlock, flags);
 		ch->protocol = ISDN_P_NONE;
--- a/drivers/isdn/hardware/mISDN/netjet.c
+++ b/drivers/isdn/hardware/mISDN/netjet.c
@@ -812,8 +812,9 @@ nj_bctrl(struct mISDNchannel *ch, u32 cm
 	switch (cmd) {
 	case CLOSE_CHANNEL:
 		test_and_clear_bit(FLG_OPEN, &bch->Flags);
+		cancel_work_sync(&bch->workq);
 		spin_lock_irqsave(&card->lock, flags);
-		mISDN_freebchannel(bch);
+		mISDN_clear_bchannel(bch);
 		mode_tiger(bc, ISDN_P_NONE);
 		spin_unlock_irqrestore(&card->lock, flags);
 		ch->protocol = ISDN_P_NONE;
--- a/drivers/isdn/hardware/mISDN/w6692.c
+++ b/drivers/isdn/hardware/mISDN/w6692.c
@@ -1054,8 +1054,9 @@ w6692_bctrl(struct mISDNchannel *ch, u32
 	switch (cmd) {
 	case CLOSE_CHANNEL:
 		test_and_clear_bit(FLG_OPEN, &bch->Flags);
+		cancel_work_sync(&bch->workq);
 		spin_lock_irqsave(&card->lock, flags);
-		mISDN_freebchannel(bch);
+		mISDN_clear_bchannel(bch);
 		w6692_mode(bc, ISDN_P_NONE);
 		spin_unlock_irqrestore(&card->lock, flags);
 		ch->protocol = ISDN_P_NONE;
--- a/drivers/isdn/mISDN/hwchannel.c
+++ b/drivers/isdn/mISDN/hwchannel.c
@@ -148,17 +148,16 @@ mISDN_clear_bchannel(struct bchannel *ch
 	ch->next_minlen = ch->init_minlen;
 	ch->maxlen = ch->init_maxlen;
 	ch->next_maxlen = ch->init_maxlen;
+	skb_queue_purge(&ch->rqueue);
+	ch->rcount = 0;
 }
 EXPORT_SYMBOL(mISDN_clear_bchannel);
 
-int
+void
 mISDN_freebchannel(struct bchannel *ch)
 {
+	cancel_work_sync(&ch->workq);
 	mISDN_clear_bchannel(ch);
-	skb_queue_purge(&ch->rqueue);
-	ch->rcount = 0;
-	flush_work_sync(&ch->workq);
-	return 0;
 }
 EXPORT_SYMBOL(mISDN_freebchannel);
 
--- a/include/linux/mISDNhw.h
+++ b/include/linux/mISDNhw.h
@@ -183,7 +183,7 @@ extern int	mISDN_initbchannel(struct bch
 				   unsigned short);
 extern int	mISDN_freedchannel(struct dchannel *);
 extern void	mISDN_clear_bchannel(struct bchannel *);
-extern int	mISDN_freebchannel(struct bchannel *);
+extern void	mISDN_freebchannel(struct bchannel *);
 extern int	mISDN_ctrl_bchannel(struct bchannel *, struct mISDN_ctrl_req *);
 extern void	queue_ch_frame(struct mISDNchannel *, u_int,
 			int, struct sk_buff *);


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