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Commit 68a360e8 authored by Willem de Bruijn's avatar Willem de Bruijn Committed by David S. Miller
Browse files

packet: remove deprecated syststamp timestamp 



No device driver will ever return an skb_shared_info structure with
syststamp non-zero, so remove the branch that tests for this and
optionally marks the packet timestamp as TP_STATUS_TS_SYS_HARDWARE.

Do not remove the definition TP_STATUS_TS_SYS_HARDWARE, as processes
may refer to it.

Signed-off-by: default avatarWillem de Bruijn <willemb@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent ce750588

Documentation/networking/packet_mmap.txt

+6 −12
Original line number Diff line number Diff line
@@ -1008,14 +1008,9 @@ hardware timestamps to be used. Note: you may need to enable the generation 
of hardware timestamps with SIOCSHWTSTAMP (see related information from

Documentation/networking/timestamping.txt).



PACKET_TIMESTAMP accepts the same integer bit field as

SO_TIMESTAMPING.  However, only the SOF_TIMESTAMPING_SYS_HARDWARE

and SOF_TIMESTAMPING_RAW_HARDWARE values are recognized by

PACKET_TIMESTAMP.  SOF_TIMESTAMPING_SYS_HARDWARE takes precedence over

SOF_TIMESTAMPING_RAW_HARDWARE if both bits are set.



    int req = 0;

    req |= SOF_TIMESTAMPING_SYS_HARDWARE;

PACKET_TIMESTAMP accepts the same integer bit field as SO_TIMESTAMPING:



    int req = SOF_TIMESTAMPING_RAW_HARDWARE;

    setsockopt(fd, SOL_PACKET, PACKET_TIMESTAMP, (void *) &req, sizeof(req))



For the mmap(2)ed ring buffers, such timestamps are stored in the
@@ -1023,14 +1018,13 @@ tpacket{,2,3}_hdr structure's tp_sec and tp_{n,u}sec members. To determine 
what kind of timestamp has been reported, the tp_status field is binary |'ed

with the following possible bits ...



    TP_STATUS_TS_SYS_HARDWARE

    TP_STATUS_TS_RAW_HARDWARE

    TP_STATUS_TS_SOFTWARE



... that are equivalent to its SOF_TIMESTAMPING_* counterparts. For the

RX_RING, if none of those 3 are set (i.e. PACKET_TIMESTAMP is not set),

then this means that a software fallback was invoked *within* PF_PACKET's

processing code (less precise).

RX_RING, if neither is set (i.e. PACKET_TIMESTAMP is not set), then a

software fallback was invoked *within* PF_PACKET's processing code (less

precise).



Getting timestamps for the TX_RING works as follows: i) fill the ring frames,

ii) call sendto() e.g. in blocking mode, iii) wait for status of relevant

include/uapi/linux/if_packet.h

+1 −1
Original line number Diff line number Diff line
@@ -108,7 +108,7 @@ struct tpacket_auxdata { 


/* Rx and Tx ring - header status */

#define TP_STATUS_TS_SOFTWARE		(1 << 29)

#define TP_STATUS_TS_SYS_HARDWARE	(1 << 30)

#define TP_STATUS_TS_SYS_HARDWARE	(1 << 30) /* deprecated, never set */

#define TP_STATUS_TS_RAW_HARDWARE	(1 << 31)



/* Rx ring - feature request bits */

net/packet/af_packet.c

+4 −8
Original line number Diff line number Diff line
@@ -441,14 +441,10 @@ static __u32 tpacket_get_timestamp(struct sk_buff *skb, struct timespec *ts, 
{

	struct skb_shared_hwtstamps *shhwtstamps = skb_hwtstamps(skb);



	if (shhwtstamps) {

		if ((flags & SOF_TIMESTAMPING_SYS_HARDWARE) &&

		    ktime_to_timespec_cond(shhwtstamps->syststamp, ts))

			return TP_STATUS_TS_SYS_HARDWARE;

		if ((flags & SOF_TIMESTAMPING_RAW_HARDWARE) &&

	if (shhwtstamps &&

	    (flags & SOF_TIMESTAMPING_RAW_HARDWARE) &&

	    ktime_to_timespec_cond(shhwtstamps->hwtstamp, ts))

		return TP_STATUS_TS_RAW_HARDWARE;

	}



	if (ktime_to_timespec_cond(skb->tstamp, ts))

		return TP_STATUS_TS_SOFTWARE;