[PATCH] fix moxa crash with more than one 1 board

ChangeSet 1.1511, 2005/04/30 11:05:23-03:00, [email protected]

	[PATCH] fix moxa crash with more than one 1 board
	
	SYMPTOMS:
	The current Moxa Intellio driver (moxa.c) panics when using > 1 board.
	
	BACKGROUND:
	The Moxa board needs a firmware download (see
	http://www.moxa.com/drivers/C320T/Linux/v5.4/MXDRV.TGZ, command
	moxaload -y) prior to usage.
	
	Unfortunately, the current Linux kernel code fails during this download if
	more than one board are installed.
	
	EXPLANATION AND FIX:
	The MoxaDriverPoll function does:
	[...]
	        for (card = 0; card < MAX_BOARDS; card++) {
	                if ((ports = moxa_boards[card].numPorts) == 0)
	                        continue;
	                if (readb(moxaIntPend[card]) == 0xff) {
	[...]
	
	Unfortunately, with multiple boards, there exists a point where
	MoxaDriverPoll() will be called when moxa_boards[card].numPorts != 0 but
	moxaIntPend[card] is still NULL. Result: kernel panic.
	
	Fix: use instead
	                if ((ports = moxa_boards[card].numPorts) == 0
	                    || moxaIntPend[card] == 0)
	                        continue;
	
	If someone who understands the code better than me proposes a better
	patch, I'd be delighted. [For the little story, the above patch was
	written after finding the bug in a remote location without internet access
	using a serial console for getting the panic trace...]



 moxa.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletion(-)


diff -Nru a/drivers/char/moxa.c b/drivers/char/moxa.c
--- a/drivers/char/moxa.c	2005-04-30 12:17:32 -07:00
+++ b/drivers/char/moxa.c	2005-04-30 12:17:32 -07:00
@@ -995,7 +995,8 @@
 		return;
 	}
 	for (card = 0; card < MAX_BOARDS; card++) {
-		if ((ports = MoxaPortsOfCard(card)) <= 0)
+		if ((ports = MoxaPortsOfCard(card)) <= 0
+				|| moxaIntPend[card] == 0)
 			continue;
 		ch = &moxaChannels[card * MAX_PORTS_PER_BOARD];
 		for (i = 0; i < ports; i++, ch++) {