[U-Boot] netconsole: USB Ethernet connection dropping with ping or tftpboot

["Jörg Krause" <jkrause@posteo.de>]

On Do, 2015-02-05 at 15:23 -0700, Stephen Warren wrote:
> 
> b) In ci_bounce(), the bounce buffer is only allocated if the 
> user-buffer is already aligned, and if a large-enough bounce buffer 
> wasn't previously allocated. If ci_req->b_buf was uninitialized it could 
> be non-zero (thus preventing the expected aligned allocation) yet not 
> actually aligned enough.

I can reproduce this issue now. After some "timeout sending packets to
usb ethernet" messages, the bounce buffer somehow gets corrupted.
ci_bounce() is called with an unaligned input buffer length
'req->length=66', but the bounce buffer length
'ci_req->b_len=1140305940' or in hex 'ci_req->b_len=0x43f7b014'. This
bounce buffer length is obviously an address, as the following
misaligned error message shows: "CACHE: Misaligned operation at range
[43f7b010, 43f7b070]".

Both if conditions in 'align:' are not entered.

This is a snippet from my debug output:

        timeout sending packets to usb ethernet
        1: 43b7e180 - 43b7e200.
        req->length: 66
        b_len_1: 96
        b_len_2: 96
        5: 43b7e660 - 43b7e6c0
        
        timeout sending packets to usb ethernet
        1: 43b7e000 - 43b7e080.
        req->length: 66
        b_len_1: 1140305940
        b_len_2: 1140305940
        5: 43f7b010 - 43f7b070
        CACHE: Misaligned operation at range [43f7b010, 43f7b070]
        timeout sending packets to usb ethernet
        ping failed; host 10.0.0.1 is not alive


This is the corresponding code (debug number 1 and 5):

        static void ci_flush_qh(int ep_num)
        {
        	struct ept_queue_head *head = ci_get_qh(ep_num, 0);
        	const uint32_t start = (uint32_t)head;
        	const uint32_t end = start + 2 * sizeof(*head);
        
        	printf("1: %x - %x.\n", start, end);
        	flush_dcache_range(start, end);
        }

[..]

        static int ci_bounce(struct ci_req *ci_req, int in)
        {
        	struct usb_request *req = &ci_req->req;
        	uint32_t addr = (uint32_t)req->buf;
        	uint32_t hwaddr;
        	uint32_t aligned_used_len;
        
        	/* Input buffer address is not aligned. */
        	if (addr & (ARCH_DMA_MINALIGN - 1)) {
        		goto align;
        	}
        
        	/* Input buffer length is not aligned. */
        	if (req->length & (ARCH_DMA_MINALIGN - 1)) {
        		printf("req->length: %d\n", req->length);
        		goto align;
        	}
        
        	/* The buffer is well aligned, only flush cache. */
        	ci_req->hw_len = req->length;
        	ci_req->hw_buf = req->buf;
        	goto flush;
        
        align:
        	printf("b_len_1: %d\n", ci_req->b_len);
        	if (ci_req->b_buf && req->length > ci_req->b_len) {
        		printf("A: %d - %d\n", req->length,  ci_req->b_len);
        		free(ci_req->b_buf);
        		ci_req->b_buf = 0;
        	}
        	if (!ci_req->b_buf) {
        		ci_req->b_len = roundup(req->length, ARCH_DMA_MINALIGN);
        		ci_req->b_buf = memalign(ARCH_DMA_MINALIGN, ci_req->b_len);
        		printf("B: %d - %d\n", req->length,  ci_req->b_len);
        		if (!ci_req->b_buf)
        			return -ENOMEM;
        	}
        	ci_req->hw_len = ci_req->b_len;
        	ci_req->hw_buf = ci_req->b_buf;
        
        	printf("b_len_2: %d\n", ci_req->b_len);
        
        	if (in)
        		memcpy(ci_req->hw_buf, req->buf, req->length);
        
        flush:
        	hwaddr = (uint32_t)ci_req->hw_buf;
        	aligned_used_len = roundup(req->length, ARCH_DMA_MINALIGN);
        	printf("5: %x - %x\n", hwaddr, hwaddr + aligned_used_len);
        	flush_dcache_range(hwaddr, hwaddr + aligned_used_len);
        
        	return 0;
        }