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Subject[patch 21/26] i4l: fix random freezes with AVM B1 drivers

2.6.22-stable review patch. If anyone has any objections, please let us
know.

------------------
From: Karsten Keil <kkeil@suse.de>
patch 9713d9e650045f7f2afd81d58a068827be306993 in mainline.

This fix the same issue which was debbuged for the C4 controller for the B1
versions.

The capilib_ function modify or traverse a linked list without locking.

This patch extends the existing locking to the calls of these function to
prevent access to a list which is in the middle of a modification.

Signed-off-by: Karsten Keil <kkeil@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
drivers/isdn/hardware/avm/b1.c | 28 +++++++++++++---------------
1 file changed, 13 insertions(+), 15 deletions(-)
--- a/drivers/isdn/hardware/avm/b1.c
+++ b/drivers/isdn/hardware/avm/b1.c
@@ -321,12 +321,15 @@ void b1_reset_ctr(struct capi_ctr *ctrl)
avmctrl_info *cinfo = (avmctrl_info *)(ctrl->driverdata);
avmcard *card = cinfo->card;
unsigned int port = card->port;
+ unsigned long flags;

b1_reset(port);
b1_reset(port);

memset(cinfo->version, 0, sizeof(cinfo->version));
+ spin_lock_irqsave(&card->lock, flags);
capilib_release(&cinfo->ncci_head);
+ spin_unlock_irqrestore(&card->lock, flags);
capi_ctr_reseted(ctrl);
}

@@ -361,9 +364,8 @@ void b1_release_appl(struct capi_ctr *ct
unsigned int port = card->port;
unsigned long flags;

- capilib_release_appl(&cinfo->ncci_head, appl);
-
spin_lock_irqsave(&card->lock, flags);
+ capilib_release_appl(&cinfo->ncci_head, appl);
b1_put_byte(port, SEND_RELEASE);
b1_put_word(port, appl);
spin_unlock_irqrestore(&card->lock, flags);
@@ -380,27 +382,27 @@ u16 b1_send_message(struct capi_ctr *ctr
u8 subcmd = CAPIMSG_SUBCOMMAND(skb->data);
u16 dlen, retval;

+ spin_lock_irqsave(&card->lock, flags);
if (CAPICMD(cmd, subcmd) == CAPI_DATA_B3_REQ) {
retval = capilib_data_b3_req(&cinfo->ncci_head,
CAPIMSG_APPID(skb->data),
CAPIMSG_NCCI(skb->data),
CAPIMSG_MSGID(skb->data));
- if (retval != CAPI_NOERROR)
+ if (retval != CAPI_NOERROR) {
+ spin_unlock_irqrestore(&card->lock, flags);
return retval;
+ }

dlen = CAPIMSG_DATALEN(skb->data);

- spin_lock_irqsave(&card->lock, flags);
b1_put_byte(port, SEND_DATA_B3_REQ);
b1_put_slice(port, skb->data, len);
b1_put_slice(port, skb->data + len, dlen);
- spin_unlock_irqrestore(&card->lock, flags);
} else {
- spin_lock_irqsave(&card->lock, flags);
b1_put_byte(port, SEND_MESSAGE);
b1_put_slice(port, skb->data, len);
- spin_unlock_irqrestore(&card->lock, flags);
}
+ spin_unlock_irqrestore(&card->lock, flags);

dev_kfree_skb_any(skb);
return CAPI_NOERROR;
@@ -534,17 +536,17 @@ irqreturn_t b1_interrupt(int interrupt,

ApplId = (unsigned) b1_get_word(card->port);
MsgLen = b1_get_slice(card->port, card->msgbuf);
- spin_unlock_irqrestore(&card->lock, flags);
if (!(skb = alloc_skb(MsgLen, GFP_ATOMIC))) {
printk(KERN_ERR "%s: incoming packet dropped\n",
card->name);
+ spin_unlock_irqrestore(&card->lock, flags);
} else {
memcpy(skb_put(skb, MsgLen), card->msgbuf, MsgLen);
if (CAPIMSG_CMD(skb->data) == CAPI_DATA_B3_CONF)
capilib_data_b3_conf(&cinfo->ncci_head, ApplId,
CAPIMSG_NCCI(skb->data),
CAPIMSG_MSGID(skb->data));
-
+ spin_unlock_irqrestore(&card->lock, flags);
capi_ctr_handle_message(ctrl, ApplId, skb);
}
break;
@@ -554,21 +556,17 @@ irqreturn_t b1_interrupt(int interrupt,
ApplId = b1_get_word(card->port);
NCCI = b1_get_word(card->port);
WindowSize = b1_get_word(card->port);
- spin_unlock_irqrestore(&card->lock, flags);
-
capilib_new_ncci(&cinfo->ncci_head, ApplId, NCCI, WindowSize);
-
+ spin_unlock_irqrestore(&card->lock, flags);
break;

case RECEIVE_FREE_NCCI:

ApplId = b1_get_word(card->port);
NCCI = b1_get_word(card->port);
- spin_unlock_irqrestore(&card->lock, flags);
-
if (NCCI != 0xffffffff)
capilib_free_ncci(&cinfo->ncci_head, ApplId, NCCI);
-
+ spin_unlock_irqrestore(&card->lock, flags);
break;

case RECEIVE_START:
--
-
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