Re: [PATCH 2/7] CAN: Add PF_CAN core module

Joe Perches [off-list ref] writes:

I'd prefer something like this, which removes the unnecessary
kmalloc/kfree pairs or the equivalent conversions to functions.

I have changed this to a static buffer.  Since this is only in
#ifdef CONFIG_CAN_DEBUG_CORE, it shouldn't hurt.

#define can_debug_cframe(cf, fmt, arg...) \
do { \
	char buf[20]; \
	int dlc = cf->can_dlc; \
	if (dlc > 8) \
		dlc = 8; \
	if (cf->can_id & CAN_EFF_FLAG) \
		sprintf(buf, "<%08X> [%X] ", cf->can_id & CAN_EFF_MASK, dlc); \
	else \
		sprintf(buf, "<%03X> [%X] ", cf->can_id & CAN_SFF_MASK, dlc); \
	printk(KERN_DEBUG fmt, ##arg); \
	print_hex_dump(buf, DUMP_PREFIX_NONE, cf->data, dlc); \
} while (0)

The line isn't printed atomically, i.e. it could happen that something
is printed between the fmt+args and the hexdump, i.e inbetween the
line.

and

#define can_debug_skb(skb) \
do { \
	pr_debug("skbuff at %p, dev: %d, proto: %04x\n", \
		 skb, skb->dev ? skb->dev->ifindex : -1, \
		 ntohs(skb->protocol)); \
	pr_debug("users: %d, dataref: %d, nr_frags: %d, " \
		 "h,d,t,e,l: %p %+d %+d %+d, %d\n", \
		 atomic_read(&skb->users), \
		 atomic_read(&(skb_shinfo(skb)->dataref)), \
		 skb_shinfo(skb)->nr_frags, \
		 skb->head, skb->data - skb->head, \
		 skb->tail - skb->head, skb->end - skb->head, skb->len); \
	print_hex_dump(KERN_DEBUG, "skb_head: ", DUMP_PREFIX_NONE, \
		       16, 1, skb->head, skb->end - skb->head); \ 
} while (0)

Here, the consecutive lines aren't printed atomically.

I think sprintf() to a buffer first and the do one printk() is
better.  But I will use hex_dump_to_buffer().


urs