On 04/28/2014 08:12 PM, Carsten Andrich wrote: > Am Montag, den 28.04.2014, 13:28 -0400 schrieb Neil Horman: >> Rather than 'lingernig' perhaps more exact language to indicate that positive >> action is required from the application. Perhaps: >> >> Packets in the WRONG_FORMAT state block the kernel from sending it and subsequent >> packets on the ring. Packet in the WRONG_FORMAT state must be moved to the >> AVAILABLE or SEND_REQUEST state (after correcting format errors), so that the >> next application call to send() properly transmits the frame. > > Thanks for the suggestion! I incorporated it into the following updated > PACKET_LOSS description: > When a malformed packet is encountered on a transmit ring, the default > is to reset its tp_status to TP_STATUS_WRONG_FORMAT and abort the > transmission immediately. The malformed packet blocks itself and > subsequent enqueued packets from being sent. The format error must be > fixed, the associated tp_status reset to TP_STATUS_SEND_REQUEST and the > transmission process restarted via send(2). However, if PACKET_LOSS is > set, any malformed packet will be skipped, its tp_status reset to > TP_STATUS_AVAILABLE, and the transmission process continued. > > IMHO this should go into the PACKET_TX_RING description, but I'd like to > defer that until I have a little more spare time on my hands, so I can > tackle the entire PACKET_MMAP-related part of the man-page in a single > effort. Carsten, Patch applied, with Neil's Ack. I added a Signed-off-by: line for you, okay? Thanks for the patch! Cheers, Michael > diff --git a/man2/getsockopt.2 b/man2/getsockopt.2 > index 925fa90..1287efc 100644 > --- a/man2/getsockopt.2 > +++ b/man2/getsockopt.2 > @@ -41,7 +41,7 @@ > .\" Modified 1999 by Andi Kleen <ak@xxxxxx>. > .\" Removed most stuff because it is in socket.7 now. > .\" > -.TH GETSOCKOPT 2 2014-01-24 "Linux" "Linux Programmer's Manual" > +.TH GETSOCKOPT 2 2014-04-28 "Linux" "Linux Programmer's Manual" > .SH NAME > getsockopt, setsockopt \- get and set options on sockets > .SH SYNOPSIS > @@ -205,6 +205,7 @@ system. > .BR getprotoent (3), > .BR protocols (5), > .BR ip (7), > +.BR packet (7), > .BR socket (7), > .BR tcp (7), > .BR udp (7), > diff --git a/man7/packet.7 b/man7/packet.7 > index 11bca48..fc5fdaf 100644 > --- a/man7/packet.7 > +++ b/man7/packet.7 > @@ -9,7 +9,7 @@ > .\" > .\" $Id: packet.7,v 1.13 2000/08/14 08:03:45 ak Exp $ > .\" > -.TH PACKET 7 2014-04-24 "Linux" "Linux Programmer's Manual" > +.TH PACKET 7 2014-04-28 "Linux" "Linux Programmer's Manual" > .SH NAME > packet \- packet interface on device level > .SH SYNOPSIS > @@ -319,14 +319,25 @@ original fanout algorithm selects a backlogged socket, the packet > rolls over to the next available one. > .TP > .BR PACKET_LOSS " (with " PACKET_TX_RING ) > -When a malformed packet is encountered on a transmit ring, the default is to > -set its status to > +When a malformed packet is encountered on a transmit ring, the default is > +to reset its > +.I tp_status > +to > .BR TP_STATUS_WRONG_FORMAT > -and abort the transmission immediately (it and following packets are left > -lingering on the ring). > +and abort the transmission immediately. > +The malformed packet blocks itself and subsequent enqueued packets from > +being sent. > +The format error must be fixed, the associated > +.I tp_status > +reset to > +.BR TP_STATUS_SEND_REQUEST > +and the transmission process restarted via > +.BR send (2) . > However, if > .BR PACKET_LOSS > -is set, any malformed packet will be skipped, its status reset to > +is set, any malformed packet will be skipped, its > +.I tp_status > +reset to > .BR TP_STATUS_AVAILABLE , > and the transmission process continued. > .TP > @@ -360,15 +371,21 @@ Packet socket and application communicate the head and tail of the ring > through the > .I tp_status > field. > -The packet socket owns all slots with status > +The packet socket owns all slots with > +.I tp_status > +equal to > .BR TP_STATUS_KERNEL . > After filling a slot, it changes the status of the slot to transfer > ownership to the application. > -During normal operation, the new status has the > +During normal operation, the new > +.I tp_status > +value has at least the > .BR TP_STATUS_USER > bit set to signal that a received packet has been stored. > When the application has finished processing a packet, it transfers > -ownership of the slot back to the socket by setting the status to > +ownership of the slot back to the socket by setting > +.I tp_status > +equal to > .BR TP_STATUS_KERNEL . > Packet sockets implement multiple variants of the packet ring. > The implementation details are described in > @@ -407,9 +424,13 @@ Create a memory-mapped ring buffer for packet transmission. > This option is similar to > .BR PACKET_RX_RING > and takes the same arguments. > -The application writes packets into slots with status > +The application writes packets into slots with > +.I tp_status > +equal to > .BR TP_STATUS_AVAILABLE > -and schedules them for transmission by changing the status to > +and schedules them for transmission by changing > +.I tp_status > +to > .BR TP_STATUS_SEND_REQUEST . > When packets are ready to be transmitted, the application calls > .BR send (2) > @@ -424,7 +445,9 @@ If an address is passed using > or > .BR sendmsg (2), > then that overrides the socket default. > -On successful transmission, the socket resets the slot to > +On successful transmission, the socket resets > +.I tp_status > +to > .BR TP_STATUS_AVAILABLE . > It immediately aborts the transmission on error unless > .BR PACKET_LOSS > @@ -633,6 +656,11 @@ The > .I <linux/if_ether.h> > include file for physical layer protocols. > > -The example source file > +The Linux kernel source tree. > +.IR /Documentation/networking/filter.txt > +describes how to apply Berkeley Packet Filters to packet sockets. > .IR /tools/testing/selftests/net/psock_tpacket.c > -in the Linux kernel source tree. > +contains example source code for all available versions of > +.BR PACKET_RX_RING > +and > +.BR PACKET_TX_RING . > > -- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Linux/UNIX System Programming Training: http://man7.org/training/ -- To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
