* [dpdk-dev] Segmentation Fault on printf() @ 2014-03-14 10:27 sabu kurian 2014-03-14 16:10 ` Chris Wright 0 siblings, 1 reply; 4+ messages in thread From: sabu kurian @ 2014-03-14 10:27 UTC (permalink / raw) To: dev Hello friends, I'm trying to print the ether_type for a packet that I captured from a port on my machine. Suppose 'm' holds the packet. 'm' is of type 'struct rte_mbuf'. Intels API reference for DPDK says 'ether_type' is of uint16_t. I used the following code to retrieve ether_type. void * eth_type; struct ether_hdr *eth; eth = rte_pktmbuf_mtod(m, struct ether_hdr *); eth_type = ð->ether_type; printf("\n Type is %" PRIu16 , *((uint16_t *)eth_type)); rte_pktmbuf_free(m); I get a 'Segmentation fault' when the printf() statement gets executed. Where am I going wrong ? Thanks in advance ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [dpdk-dev] Segmentation Fault on printf() 2014-03-14 10:27 [dpdk-dev] Segmentation Fault on printf() sabu kurian @ 2014-03-14 16:10 ` Chris Wright 2014-03-16 13:03 ` sabu kurian 0 siblings, 1 reply; 4+ messages in thread From: Chris Wright @ 2014-03-14 16:10 UTC (permalink / raw) To: sabu kurian; +Cc: dev * sabu kurian (sabu2kurian@gmail.com) wrote: > Hello friends, > > I'm trying to print the ether_type for a packet that I captured from a port > on my machine. Suppose 'm' holds the packet. 'm' is of type 'struct > rte_mbuf'. Intels API reference for DPDK says 'ether_type' is of uint16_t. > I used the following code to retrieve ether_type. > > void * eth_type; > struct ether_hdr *eth; > > eth = rte_pktmbuf_mtod(m, struct ether_hdr *); > eth_type = ð->ether_type; > > printf("\n Type is %" PRIu16 , *((uint16_t *)eth_type)); Looks ok, albeit slightly overly complicated. struct ether_hdr *eth; uint16_t eth_type; eth = rte_pktmbuf_mtod(m, struct ether_hdr *); eth_type = eth->ether_type; printf("\n Type is %" PRIu16 , eth_type)); This would remove all the extra casting. Perhaps the mbuf is the problem here. And if so, the above snippet would segfault on eth->ether_type showing you that mbuf is invalid. You could try to (above mtod): rte_pktmbuf_dump(m, sizeof(struct ether_hdr)); as that will show key contents of mbuf and packet data (and do some basic validation along the way). thanks, -chris ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [dpdk-dev] Segmentation Fault on printf() 2014-03-14 16:10 ` Chris Wright @ 2014-03-16 13:03 ` sabu kurian 2014-03-17 19:45 ` Daniel Kaminsky 0 siblings, 1 reply; 4+ messages in thread From: sabu kurian @ 2014-03-16 13:03 UTC (permalink / raw) To: Chris Wright; +Cc: dev Hello chris, Thanks for your reply. I tried dumping the contents of mbuf as you have suggested. This is what I get: dump mbuf at 0x0x6c7620, phys=7f34d91eba28, buf_len=59488 pkt_len=0, ol_flags=0, nb_segs=0, in_port=0 and soon after that I get a segmentation fault. Do you have any idea on what could be causing it ? Regards On Fri, Mar 14, 2014 at 9:40 PM, Chris Wright <chrisw@redhat.com> wrote: > * sabu kurian (sabu2kurian@gmail.com) wrote: > > Hello friends, > > > > I'm trying to print the ether_type for a packet that I captured from a > port > > on my machine. Suppose 'm' holds the packet. 'm' is of type 'struct > > rte_mbuf'. Intels API reference for DPDK says 'ether_type' is of > uint16_t. > > I used the following code to retrieve ether_type. > > > > void * eth_type; > > struct ether_hdr *eth; > > > > eth = rte_pktmbuf_mtod(m, struct ether_hdr *); > > eth_type = ð->ether_type; > > > > printf("\n Type is %" PRIu16 , *((uint16_t *)eth_type)); > > Looks ok, albeit slightly overly complicated. > > struct ether_hdr *eth; > uint16_t eth_type; > > eth = rte_pktmbuf_mtod(m, struct ether_hdr *); > eth_type = eth->ether_type; > printf("\n Type is %" PRIu16 , eth_type)); > > This would remove all the extra casting. Perhaps the mbuf is the problem > here. And if so, the above snippet would segfault on eth->ether_type > showing you that mbuf is invalid. > > You could try to (above mtod): > > rte_pktmbuf_dump(m, sizeof(struct ether_hdr)); > > as that will show key contents of mbuf and packet data (and do some > basic validation along the way). > > thanks, > -chris > ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [dpdk-dev] Segmentation Fault on printf() 2014-03-16 13:03 ` sabu kurian @ 2014-03-17 19:45 ` Daniel Kaminsky 0 siblings, 0 replies; 4+ messages in thread From: Daniel Kaminsky @ 2014-03-17 19:45 UTC (permalink / raw) To: sabu kurian; +Cc: dev Sabu, I think that in this case the packet length is zero which will result in nothing from mtod. Daniel On Sun, Mar 16, 2014 at 3:03 PM, sabu kurian <sabu2kurian@gmail.com> wrote: > Hello chris, > > Thanks for your reply. I tried dumping the contents of mbuf as you have > suggested. > This is what I get: > > dump mbuf at 0x0x6c7620, phys=7f34d91eba28, buf_len=59488 > pkt_len=0, ol_flags=0, nb_segs=0, in_port=0 > > and soon after that I get a segmentation fault. Do you have any idea on > what could be causing it ? > > Regards > > > > On Fri, Mar 14, 2014 at 9:40 PM, Chris Wright <chrisw@redhat.com> wrote: > > > * sabu kurian (sabu2kurian@gmail.com) wrote: > > > Hello friends, > > > > > > I'm trying to print the ether_type for a packet that I captured from a > > port > > > on my machine. Suppose 'm' holds the packet. 'm' is of type 'struct > > > rte_mbuf'. Intels API reference for DPDK says 'ether_type' is of > > uint16_t. > > > I used the following code to retrieve ether_type. > > > > > > void * eth_type; > > > struct ether_hdr *eth; > > > > > > eth = rte_pktmbuf_mtod(m, struct ether_hdr *); > > > eth_type = ð->ether_type; > > > > > > printf("\n Type is %" PRIu16 , *((uint16_t *)eth_type)); > > > > Looks ok, albeit slightly overly complicated. > > > > struct ether_hdr *eth; > > uint16_t eth_type; > > > > eth = rte_pktmbuf_mtod(m, struct ether_hdr *); > > eth_type = eth->ether_type; > > printf("\n Type is %" PRIu16 , eth_type)); > > > > This would remove all the extra casting. Perhaps the mbuf is the problem > > here. And if so, the above snippet would segfault on eth->ether_type > > showing you that mbuf is invalid. > > > > You could try to (above mtod): > > > > rte_pktmbuf_dump(m, sizeof(struct ether_hdr)); > > > > as that will show key contents of mbuf and packet data (and do some > > basic validation along the way). > > > > thanks, > > -chris > > > ^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2014-03-17 19:44 UTC | newest] Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2014-03-14 10:27 [dpdk-dev] Segmentation Fault on printf() sabu kurian 2014-03-14 16:10 ` Chris Wright 2014-03-16 13:03 ` sabu kurian 2014-03-17 19:45 ` Daniel Kaminsky
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