From: Ilya Maximets <i.maximets@samsung.com>
To: "Wiles, Keith" <keith.wiles@intel.com>, "dev@dpdk.org" <dev@dpdk.org>
Cc: Dyasly Sergey <s.dyasly@samsung.com>
Subject: Re: [dpdk-dev] [Pktgen] [PATCH] pktgen_setup_packets: fix race for packet header
Date: Thu, 17 Sep 2015 08:55:11 +0300 [thread overview]
Message-ID: <55FA55BF.6000005@samsung.com> (raw)
In-Reply-To: <D21EDA83.2A795%keith.wiles@intel.com>
Ok. Thank you. I'll wait.
On 16.09.2015 18:37, Wiles, Keith wrote:
> Thanks the patch looks fine, but I have not had a lot of time to review it
> detail. I hope to get to it next week after I return back home.
>
> On 9/16/15, 2:09 AM, "Ilya Maximets" <i.maximets@samsung.com> wrote:
>
>> Ping.
>>
>> On 09.09.2015 17:22, Ilya Maximets wrote:
>>> While pktgen_setup_packets() all threads of one port uses same
>>> info->seq_pkt. This leads to constructing packets in the same memory
>>> region
>>> (&pkt->hdr). As a result, pktgen_setup_packets generates random headers.
>>>
>>> Fix that by making a local copy of info->seq_pkt and using it for
>>> constructing of packets.
>>>
>>> Signed-off-by: Ilya Maximets <i.maximets@samsung.com>
>>> ---
>>> app/pktgen-arp.c | 2 +-
>>> app/pktgen-cmds.c | 40 ++++++++++++++++++++--------------------
>>> app/pktgen-ipv4.c | 2 +-
>>> app/pktgen.c | 39 +++++++++++++++++++++++++++------------
>>> app/pktgen.h | 4 ++--
>>> app/t/pktgen.t.c | 6 +++---
>>> 6 files changed, 54 insertions(+), 39 deletions(-)
>>>
>>> diff --git a/app/pktgen-arp.c b/app/pktgen-arp.c
>>> index c378880..b7040d7 100644
>>> --- a/app/pktgen-arp.c
>>> +++ b/app/pktgen-arp.c
>>> @@ -190,7 +190,7 @@ pktgen_process_arp( struct rte_mbuf * m, uint32_t
>>> pid, uint32_t vlan )
>>>
>>> rte_memcpy(&pkt->eth_dst_addr, &arp->sha, 6);
>>> for (i = 0; i < info->seqCnt; i++)
>>> - pktgen_packet_ctor(info, i, -1);
>>> + pktgen_packet_ctor(info, i, -1, NULL);
>>> }
>>>
>>> // Swap the two MAC addresses
>>> diff --git a/app/pktgen-cmds.c b/app/pktgen-cmds.c
>>> index da040e5..a6abb41 100644
>>> --- a/app/pktgen-cmds.c
>>> +++ b/app/pktgen-cmds.c
>>> @@ -931,7 +931,7 @@ pktgen_set_proto(port_info_t * info, char type)
>>> if ( type == 'i' )
>>> info->seq_pkt[SINGLE_PKT].ethType = ETHER_TYPE_IPv4;
>>>
>>> - pktgen_packet_ctor(info, SINGLE_PKT, -1);
>>> + pktgen_packet_ctor(info, SINGLE_PKT, -1, NULL);
>>> }
>>>
>>>
>>> /************************************************************************
>>> **//**
>>> @@ -1067,7 +1067,7 @@ pktgen_set_pkt_type(port_info_t * info, const
>>> char * type)
>>> (type[3] == '6') ? ETHER_TYPE_IPv6 :
>>> /* TODO print error: unknown type */ ETHER_TYPE_IPv4;
>>>
>>> - pktgen_packet_ctor(info, SINGLE_PKT, -1);
>>> + pktgen_packet_ctor(info, SINGLE_PKT, -1, NULL);
>>> }
>>>
>>>
>>> /************************************************************************
>>> **//**
>>> @@ -1092,7 +1092,7 @@ pktgen_set_vlan(port_info_t * info, uint32_t
>>> onOff)
>>> }
>>> else
>>> pktgen_clr_port_flags(info, SEND_VLAN_ID);
>>> - pktgen_packet_ctor(info, SINGLE_PKT, -1);
>>> + pktgen_packet_ctor(info, SINGLE_PKT, -1, NULL);
>>> }
>>>
>>>
>>> /************************************************************************
>>> **//**
>>> @@ -1112,7 +1112,7 @@ pktgen_set_vlanid(port_info_t * info, uint16_t
>>> vlanid)
>>> {
>>> info->vlanid = vlanid;
>>> info->seq_pkt[SINGLE_PKT].vlanid = info->vlanid;
>>> - pktgen_packet_ctor(info, SINGLE_PKT, -1);
>>> + pktgen_packet_ctor(info, SINGLE_PKT, -1, NULL);
>>> }
>>>
>>>
>>> /************************************************************************
>>> **//**
>>> @@ -1137,7 +1137,7 @@ pktgen_set_mpls(port_info_t * info, uint32_t
>>> onOff)
>>> }
>>> else
>>> pktgen_clr_port_flags(info, SEND_MPLS_LABEL);
>>> - pktgen_packet_ctor(info, SINGLE_PKT, -1);
>>> + pktgen_packet_ctor(info, SINGLE_PKT, -1, NULL);
>>> }
>>>
>>>
>>> /************************************************************************
>>> **//**
>>> @@ -1157,7 +1157,7 @@ pktgen_set_mpls_entry(port_info_t * info,
>>> uint32_t mpls_entry)
>>> {
>>> info->mpls_entry = mpls_entry;
>>> info->seq_pkt[SINGLE_PKT].mpls_entry = info->mpls_entry;
>>> - pktgen_packet_ctor(info, SINGLE_PKT, -1);
>>> + pktgen_packet_ctor(info, SINGLE_PKT, -1, NULL);
>>> }
>>>
>>>
>>> /************************************************************************
>>> **//**
>>> @@ -1182,7 +1182,7 @@ pktgen_set_qinq(port_info_t * info, uint32_t
>>> onOff)
>>> }
>>> else
>>> pktgen_clr_port_flags(info, SEND_Q_IN_Q_IDS);
>>> - pktgen_packet_ctor(info, SINGLE_PKT, -1);
>>> + pktgen_packet_ctor(info, SINGLE_PKT, -1, NULL);
>>> }
>>>
>>>
>>> /************************************************************************
>>> **//**
>>> @@ -1204,7 +1204,7 @@ pktgen_set_qinqids(port_info_t * info, uint16_t
>>> outerid, uint16_t innerid)
>>> info->seq_pkt[SINGLE_PKT].qinq_outerid = info->qinq_outerid;
>>> info->qinq_innerid = innerid;
>>> info->seq_pkt[SINGLE_PKT].qinq_innerid = info->qinq_innerid;
>>> - pktgen_packet_ctor(info, SINGLE_PKT, -1);
>>> + pktgen_packet_ctor(info, SINGLE_PKT, -1, NULL);
>>> }
>>>
>>>
>>> /************************************************************************
>>> **//**
>>> @@ -1228,7 +1228,7 @@ pktgen_set_gre(port_info_t * info, uint32_t onOff)
>>> }
>>> else
>>> pktgen_clr_port_flags(info, SEND_GRE_IPv4_HEADER);
>>> - pktgen_packet_ctor(info, SINGLE_PKT, -1);
>>> + pktgen_packet_ctor(info, SINGLE_PKT, -1, NULL);
>>> }
>>>
>>>
>>> /************************************************************************
>>> **//**
>>> @@ -1252,7 +1252,7 @@ pktgen_set_gre_eth(port_info_t * info, uint32_t
>>> onOff)
>>> }
>>> else
>>> pktgen_clr_port_flags(info, SEND_GRE_ETHER_HEADER);
>>> - pktgen_packet_ctor(info, SINGLE_PKT, -1);
>>> + pktgen_packet_ctor(info, SINGLE_PKT, -1, NULL);
>>> }
>>>
>>>
>>> /************************************************************************
>>> **//**
>>> @@ -1272,7 +1272,7 @@ pktgen_set_gre_key(port_info_t * info, uint32_t
>>> gre_key)
>>> {
>>> info->gre_key = gre_key;
>>> info->seq_pkt[SINGLE_PKT].gre_key = info->gre_key;
>>> - pktgen_packet_ctor(info, SINGLE_PKT, -1);
>>> + pktgen_packet_ctor(info, SINGLE_PKT, -1, NULL);
>>> }
>>>
>>>
>>> /************************************************************************
>>> **//**
>>> @@ -1401,7 +1401,7 @@ void pktgen_port_defaults(uint32_t pid, uint8_t
>>> seq)
>>> memset(&pkt->eth_dst_addr, 0, sizeof (pkt->eth_dst_addr));
>>>
>>>
>>> - pktgen_packet_ctor(info, seq, -1);
>>> + pktgen_packet_ctor(info, seq, -1, NULL);
>>>
>>> pktgen.flags |= PRINT_LABELS_FLAG;
>>> }
>>> @@ -1423,7 +1423,7 @@ void pktgen_ping4(port_info_t * info)
>>> memcpy(&info->seq_pkt[PING_PKT],
>>> &info->seq_pkt[SINGLE_PKT], sizeof(pkt_seq_t));
>>> info->seq_pkt[PING_PKT].ipProto = PG_IPPROTO_ICMP;
>>> - pktgen_packet_ctor(info, PING_PKT, ICMP4_ECHO);
>>> + pktgen_packet_ctor(info, PING_PKT, ICMP4_ECHO, NULL);
>>> pktgen_set_port_flags(info, SEND_PING4_REQUEST);
>>> }
>>>
>>> @@ -1445,7 +1445,7 @@ void pktgen_ping6(port_info_t * info)
>>> memcpy(&info->pkt[PING_PKT],
>>> &info->pkt[SINGLE_PKT], sizeof(pkt_seq_t));
>>> info->pkt[PING_PKT].ipProto = PG_IPPROTO_ICMP;
>>> - pktgen_packet_ctor(info, PING_PKT, ICMP6_ECHO);
>>> + pktgen_packet_ctor(info, PING_PKT, ICMP6_ECHO, NULL);
>>> pktgen_set_port_flags(info, SEND_PING6_REQUEST);
>>> }
>>> #endif
>>> @@ -1645,7 +1645,7 @@ void pktgen_set_pkt_size(port_info_t * info,
>>> uint32_t size)
>>> else if ( (size - FCS_SIZE) > MAX_PKT_SIZE)
>>> size = MAX_PKT_SIZE + FCS_SIZE;
>>> info->seq_pkt[SINGLE_PKT].pktSize = (size - FCS_SIZE);
>>> - pktgen_packet_ctor(info, SINGLE_PKT, -1);
>>> + pktgen_packet_ctor(info, SINGLE_PKT, -1, NULL);
>>> pktgen_packet_rate(info);
>>> }
>>>
>>> @@ -1667,7 +1667,7 @@ void pktgen_set_port_value(port_info_t * info,
>>> char type, uint32_t portValue)
>>> info->seq_pkt[SINGLE_PKT].dport = (uint16_t)portValue;
>>> else
>>> info->seq_pkt[SINGLE_PKT].sport = (uint16_t)portValue;
>>> - pktgen_packet_ctor(info, SINGLE_PKT, -1);
>>> + pktgen_packet_ctor(info, SINGLE_PKT, -1, NULL);
>>> }
>>>
>>>
>>> /************************************************************************
>>> **//**
>>> @@ -1711,7 +1711,7 @@ void pktgen_set_ipaddr(port_info_t * info, char
>>> type, cmdline_ipaddr_t * ip)
>>> info->seq_pkt[SINGLE_PKT].ip_src_addr = ntohl(ip->addr.ipv4.s_addr);
>>> } else
>>> info->seq_pkt[SINGLE_PKT].ip_dst_addr = ntohl(ip->addr.ipv4.s_addr);
>>> - pktgen_packet_ctor(info, SINGLE_PKT, -1);
>>> + pktgen_packet_ctor(info, SINGLE_PKT, -1, NULL);
>>> }
>>>
>>>
>>> /************************************************************************
>>> **//**
>>> @@ -1729,7 +1729,7 @@ void pktgen_set_ipaddr(port_info_t * info, char
>>> type, cmdline_ipaddr_t * ip)
>>> void pktgen_set_dst_mac(port_info_t * info, cmdline_etheraddr_t * mac)
>>> {
>>> memcpy(&info->seq_pkt[SINGLE_PKT].eth_dst_addr, mac->mac, 6);
>>> - pktgen_packet_ctor(info, SINGLE_PKT, -1);
>>> + pktgen_packet_ctor(info, SINGLE_PKT, -1, NULL);
>>> }
>>>
>>>
>>> /************************************************************************
>>> **//**
>>> @@ -2111,7 +2111,7 @@ void pktgen_set_seq(port_info_t * info, uint32_t
>>> seqnum,
>>> type = '4';
>>> pkt->ethType = (type == '6')? ETHER_TYPE_IPv6 : ETHER_TYPE_IPv4;
>>> pkt->vlanid = vlanid;
>>> - pktgen_packet_ctor(info, seqnum, -1);
>>> + pktgen_packet_ctor(info, seqnum, -1, NULL);
>>> }
>>>
>>>
>>> /************************************************************************
>>> **//**
>>> @@ -2156,7 +2156,7 @@ void pktgen_compile_pkt(port_info_t * info,
>>> uint32_t seqnum,
>>> (type == '6')? ETHER_TYPE_IPv6 :
>>> (type == 'n')? ETHER_TYPE_VLAN : ETHER_TYPE_IPv4;
>>> pkt->vlanid = vlanid;
>>> - pktgen_packet_ctor(info, seqnum, -1);
>>> + pktgen_packet_ctor(info, seqnum, -1, NULL);
>>> }
>>>
>>>
>>> /************************************************************************
>>> **//**
>>> diff --git a/app/pktgen-ipv4.c b/app/pktgen-ipv4.c
>>> index 7813c36..a8b6be2 100644
>>> --- a/app/pktgen-ipv4.c
>>> +++ b/app/pktgen-ipv4.c
>>> @@ -138,7 +138,7 @@ pktgen_send_ping4( uint32_t pid, uint8_t seq_idx )
>>> return;
>>> }
>>> *ppkt = *spkt; // Copy the sequence setup to the ping setup.
>>> - pktgen_packet_ctor(info, PING_PKT, ICMP4_ECHO);
>>> + pktgen_packet_ctor(info, PING_PKT, ICMP4_ECHO, NULL);
>>> rte_memcpy((uint8_t *)m->buf_addr + m->data_off, (uint8_t
>>> *)&ppkt->hdr, ppkt->pktSize);
>>>
>>> m->pkt_len = ppkt->pktSize;
>>> diff --git a/app/pktgen.c b/app/pktgen.c
>>> index 2dcdbfd..ecd4560 100644
>>> --- a/app/pktgen.c
>>> +++ b/app/pktgen.c
>>> @@ -401,8 +401,8 @@ static __inline__ int pktgen_has_work(void) {
>>> */
>>>
>>> void
>>> -pktgen_packet_ctor(port_info_t * info, int32_t seq_idx, int32_t type) {
>>> - pkt_seq_t * pkt = &info->seq_pkt[seq_idx];
>>> +pktgen_packet_ctor(port_info_t * info, int32_t seq_idx, int32_t type,
>>> pkt_seq_t * seq_pkt) {
>>> + pkt_seq_t * pkt = (seq_pkt == NULL) ? &info->seq_pkt[seq_idx] :
>>> &seq_pkt[seq_idx];
>>> struct ether_hdr * eth = (struct ether_hdr *)&pkt->hdr.eth;
>>> uint16_t tlen;
>>>
>>> @@ -812,22 +812,35 @@ static __inline__ void
>>> pktgen_setup_packets(port_info_t * info, struct rte_mempool * mp,
>>> uint16_t qid)
>>> {
>>> struct rte_mbuf * m, * mm;
>>> - pkt_seq_t * pkt;
>>> + pkt_seq_t * pkt, * seq_pkt = NULL;
>>> + uint16_t seqIdx;
>>> + char buff[RTE_MEMZONE_NAMESIZE];
>>>
>>> pktgen_clr_q_flags(info, qid, CLEAR_FAST_ALLOC_FLAG);
>>>
>>> if ( mp == info->q[qid].pcap_mp )
>>> return;
>>>
>>> + snprintf(buff, sizeof(buff), "tmp_seq_pkt_%d_%d", info->pid, qid);
>>> + seq_pkt = (pkt_seq_t *)rte_zmalloc(buff,
>>> + (sizeof(pkt_seq_t) * NUM_TOTAL_PKTS), RTE_CACHE_LINE_SIZE);
>>> + if (seq_pkt == NULL)
>>> + pktgen_log_panic("Unable to allocate %d pkt_seq_t headers",
>>> + NUM_TOTAL_PKTS);
>>> + /* Copy global configuration to construct new packets locally */
>>> + rte_memcpy((uint8_t *)seq_pkt, (uint8_t *)info->seq_pkt,
>>> + sizeof(pkt_seq_t) * NUM_TOTAL_PKTS);
>>> + seqIdx = info->seqIdx;
>>> +
>>> mm = NULL;
>>> pkt = NULL;
>>>
>>> if ( mp == info->q[qid].tx_mp )
>>> - pkt = &info->seq_pkt[SINGLE_PKT];
>>> + pkt = &seq_pkt[SINGLE_PKT];
>>> else if ( mp == info->q[qid].range_mp )
>>> - pkt = &info->seq_pkt[RANGE_PKT];
>>> + pkt = &seq_pkt[RANGE_PKT];
>>> else if ( mp == info->q[qid].seq_mp )
>>> - pkt = &info->seq_pkt[info->seqIdx];
>>> + pkt = &seq_pkt[seqIdx];
>>>
>>> // allocate each mbuf and put them on a list to be freed.
>>> for(;;) {
>>> @@ -840,7 +853,7 @@ pktgen_setup_packets(port_info_t * info, struct
>>> rte_mempool * mp, uint16_t qid)
>>> mm = m;
>>>
>>> if ( mp == info->q[qid].tx_mp ) {
>>> - pktgen_packet_ctor(info, SINGLE_PKT, -1);
>>> + pktgen_packet_ctor(info, SINGLE_PKT, -1, seq_pkt);
>>>
>>> rte_memcpy((uint8_t *)m->buf_addr + m->data_off, (uint8_t
>>> *)&pkt->hdr, MAX_PKT_SIZE);
>>>
>>> @@ -848,16 +861,16 @@ pktgen_setup_packets(port_info_t * info, struct
>>> rte_mempool * mp, uint16_t qid)
>>> m->data_len = pkt->pktSize;
>>> } else if ( mp == info->q[qid].range_mp ) {
>>> pktgen_range_ctor(&info->range, pkt);
>>> - pktgen_packet_ctor(info, RANGE_PKT, -1);
>>> + pktgen_packet_ctor(info, RANGE_PKT, -1, seq_pkt);
>>>
>>> rte_memcpy((uint8_t *)m->buf_addr + m->data_off, (uint8_t
>>> *)&pkt->hdr, MAX_PKT_SIZE);
>>>
>>> m->pkt_len = pkt->pktSize;
>>> m->data_len = pkt->pktSize;
>>> } else if ( mp == info->q[qid].seq_mp ) {
>>> - pktgen_packet_ctor(info, info->seqIdx++, -1);
>>> - if ( unlikely(info->seqIdx >= info->seqCnt) )
>>> - info->seqIdx = 0;
>>> + pktgen_packet_ctor(info, seqIdx++, -1, seq_pkt);
>>> + if ( unlikely(seqIdx >= info->seqCnt) )
>>> + seqIdx = 0;
>>>
>>> rte_memcpy((uint8_t *)m->buf_addr + m->data_off, (uint8_t
>>> *)&pkt->hdr, MAX_PKT_SIZE);
>>>
>>> @@ -865,12 +878,14 @@ pktgen_setup_packets(port_info_t * info, struct
>>> rte_mempool * mp, uint16_t qid)
>>> m->data_len = pkt->pktSize;
>>>
>>> // move to the next packet in the sequence.
>>> - pkt = &info->seq_pkt[info->seqIdx];
>>> + pkt = &seq_pkt[seqIdx];
>>> }
>>> }
>>>
>>> if ( mm != NULL )
>>> rte_pktmbuf_free(mm);
>>> +
>>> + rte_free(seq_pkt);
>>> }
>>>
>>>
>>> /************************************************************************
>>> **//**
>>> diff --git a/app/pktgen.h b/app/pktgen.h
>>> index 2c5c98c..f3f76f2 100644
>>> --- a/app/pktgen.h
>>> +++ b/app/pktgen.h
>>> @@ -151,7 +151,7 @@
>>> #include "pktgen-port-cfg.h"
>>> #include "pktgen-capture.h"
>>> #include "pktgen-log.h"
>>> -
>>> +#include "pktgen-seq.h"
>>>
>>> #define PKTGEN_VERSION "2.9.2"
>>> #define PKTGEN_APP_NAME "Pktgen"
>>> @@ -386,7 +386,7 @@ extern pktgen_t pktgen;
>>>
>>> extern void pktgen_page_display(__attribute__((unused)) struct
>>> rte_timer *tim, __attribute__((unused)) void *arg);
>>>
>>> -extern void pktgen_packet_ctor(port_info_t * info, int32_t seq_idx,
>>> int32_t type);
>>> +extern void pktgen_packet_ctor(port_info_t * info, int32_t seq_idx,
>>> int32_t type, pkt_seq_t * seq_pkt);
>>> extern void pktgen_packet_rate(port_info_t * info);
>>>
>>> extern void pktgen_send_mbuf(struct rte_mbuf *m, uint8_t pid, uint16_t
>>> qid);
>>> diff --git a/app/t/pktgen.t.c b/app/t/pktgen.t.c
>>> index 0eca4c4..77bf300 100644
>>> --- a/app/t/pktgen.t.c
>>> +++ b/app/t/pktgen.t.c
>>> @@ -77,7 +77,7 @@ void test_pktgen_packet_ctor_IPv4_UDP(void)
>>> };
>>>
>>>
>>> - lives_ok( { pktgen_packet_ctor(&info, 0, 0); }, "pktgen_packet_ctor
>>> must generate IPv4/UDP");
>>> + lives_ok( { pktgen_packet_ctor(&info, 0, 0, NULL); },
>>> "pktgen_packet_ctor must generate IPv4/UDP");
>>>
>>> note("... with Ethernet header");
>>> cmp_mem_lit_incr(data, (0xdd, 0xdd, 0xdd, 0xdd, 0xdd, 0xdd), " ...
>>> with correct dest MAC");
>>> @@ -133,9 +133,9 @@ void test_pktgen_packet_ctor_IPv4_GRE_Ether(void)
>>> .pktSize = 102, // Subtract 4 for FCS
>>> };
>>>
>>> - pktgen_packet_ctor(&info, 0, 0);
>>> + pktgen_packet_ctor(&info, 0, 0, NULL);
>>>
>>> - lives_ok( { pktgen_packet_ctor(&info, 0, 0); }, "pktgen_packet_ctor
>>> must generate IPv4 GRE Ethernet frame");
>>> + lives_ok( { pktgen_packet_ctor(&info, 0, 0, NULL); },
>>> "pktgen_packet_ctor must generate IPv4 GRE Ethernet frame");
>>>
>>> note("... with outer Ethernet header");
>>> cmp_mem_lit_incr(data, (0xdd, 0xdd, 0xdd, 0xdd, 0xdd, 0xdd), " ...
>>> with correct dest MAC");
>>>
>>
>
>
> ‹
> Regards,
> ++Keith
> Intel Corporation
>
>
>
>
next prev parent reply other threads:[~2015-09-17 5:55 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-09-09 14:22 Ilya Maximets
2015-09-16 9:09 ` Ilya Maximets
2015-09-16 15:37 ` Wiles, Keith
2015-09-17 5:55 ` Ilya Maximets [this message]
2015-10-02 9:23 ` Ilya Maximets
2015-10-02 11:25 ` Wiles, Keith
2015-10-12 14:09 ` Ilya Maximets
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=55FA55BF.6000005@samsung.com \
--to=i.maximets@samsung.com \
--cc=dev@dpdk.org \
--cc=keith.wiles@intel.com \
--cc=s.dyasly@samsung.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).