mISDN: Fix wrong usage of flush_work_sync while holding locks

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@b1-systems.de>
Cc: <stable@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/isdn/hardware/mISDN/avmfritz.c

@@ -857,8 +857,9 @@ avm_bctrl(struct mISDNchannel *ch, u32 cmd, void *arg)
 	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;

drivers/isdn/hardware/mISDN/mISDNipac.c

@@ -1406,8 +1406,9 @@ hscx_bctrl(struct mISDNchannel *ch, u32 cmd, void *arg)
 	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;

drivers/isdn/hardware/mISDN/mISDNisar.c

@@ -1588,8 +1588,9 @@ isar_bctrl(struct mISDNchannel *ch, u32 cmd, void *arg)
 	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;

drivers/isdn/hardware/mISDN/netjet.c

@@ -812,8 +812,9 @@ nj_bctrl(struct mISDNchannel *ch, u32 cmd, void *arg)
 	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;

drivers/isdn/hardware/mISDN/w6692.c

@@ -1054,8 +1054,9 @@ w6692_bctrl(struct mISDNchannel *ch, u32 cmd, void *arg)
 	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;

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);
 

include/linux/mISDNhw.h

@@ -183,7 +183,7 @@ extern int	mISDN_initbchannel(struct bchannel *, unsigned short,
 				   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 *);