<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux.git/net/smc, branch v6.10-rc6</title>
<subtitle>Clone of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git</subtitle>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/'/>
<entry>
<title>net/smc: avoid overwriting when adjusting sock bufsizes</title>
<updated>2024-06-05T08:42:57+00:00</updated>
<author>
<name>Wen Gu</name>
<email>guwen@linux.alibaba.com</email>
</author>
<published>2024-05-31T08:54:17+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=fb0aa0781a5f457e3864da68af52c3b1f4f7fd8f'/>
<id>fb0aa0781a5f457e3864da68af52c3b1f4f7fd8f</id>
<content type='text'>
When copying smc settings to clcsock, avoid setting clcsock's sk_sndbuf
to sysctl_tcp_wmem[1], since this may overwrite the value set by
tcp_sndbuf_expand() in TCP connection establishment.

And the other setting sk_{snd|rcv}buf to sysctl value in
smc_adjust_sock_bufsizes() can also be omitted since the initialization
of smc sock and clcsock has set sk_{snd|rcv}buf to smc.sysctl_{w|r}mem
or ipv4_sysctl_tcp_{w|r}mem[1].

Fixes: 30c3c4a4497c ("net/smc: Use correct buffer sizes when switching between TCP and SMC")
Link: https://lore.kernel.org/r/5eaf3858-e7fd-4db8-83e8-3d7a3e0e9ae2@linux.alibaba.com
Signed-off-by: Wen Gu &lt;guwen@linux.alibaba.com&gt;
Reviewed-by: Wenjia Zhang &lt;wenjia@linux.ibm.com&gt;
Reviewed-by: Gerd Bayer &lt;gbayer@linux.ibm.com&gt;, too.
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
When copying smc settings to clcsock, avoid setting clcsock's sk_sndbuf
to sysctl_tcp_wmem[1], since this may overwrite the value set by
tcp_sndbuf_expand() in TCP connection establishment.

And the other setting sk_{snd|rcv}buf to sysctl value in
smc_adjust_sock_bufsizes() can also be omitted since the initialization
of smc sock and clcsock has set sk_{snd|rcv}buf to smc.sysctl_{w|r}mem
or ipv4_sysctl_tcp_{w|r}mem[1].

Fixes: 30c3c4a4497c ("net/smc: Use correct buffer sizes when switching between TCP and SMC")
Link: https://lore.kernel.org/r/5eaf3858-e7fd-4db8-83e8-3d7a3e0e9ae2@linux.alibaba.com
Signed-off-by: Wen Gu &lt;guwen@linux.alibaba.com&gt;
Reviewed-by: Wenjia Zhang &lt;wenjia@linux.ibm.com&gt;
Reviewed-by: Gerd Bayer &lt;gbayer@linux.ibm.com&gt;, too.
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>tracing/treewide: Remove second parameter of __assign_str()</title>
<updated>2024-05-23T00:14:47+00:00</updated>
<author>
<name>Steven Rostedt (Google)</name>
<email>rostedt@goodmis.org</email>
</author>
<published>2024-05-16T17:34:54+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=2c92ca849fcc6ee7d0c358e9959abc9f58661aea'/>
<id>2c92ca849fcc6ee7d0c358e9959abc9f58661aea</id>
<content type='text'>
With the rework of how the __string() handles dynamic strings where it
saves off the source string in field in the helper structure[1], the
assignment of that value to the trace event field is stored in the helper
value and does not need to be passed in again.

This means that with:

  __string(field, mystring)

Which use to be assigned with __assign_str(field, mystring), no longer
needs the second parameter and it is unused. With this, __assign_str()
will now only get a single parameter.

There's over 700 users of __assign_str() and because coccinelle does not
handle the TRACE_EVENT() macro I ended up using the following sed script:

  git grep -l __assign_str | while read a ; do
      sed -e 's/\(__assign_str([^,]*[^ ,]\) *,[^;]*/\1)/' $a &gt; /tmp/test-file;
      mv /tmp/test-file $a;
  done

I then searched for __assign_str() that did not end with ';' as those
were multi line assignments that the sed script above would fail to catch.

Note, the same updates will need to be done for:

  __assign_str_len()
  __assign_rel_str()
  __assign_rel_str_len()

I tested this with both an allmodconfig and an allyesconfig (build only for both).

[1] https://lore.kernel.org/linux-trace-kernel/20240222211442.634192653@goodmis.org/

Link: https://lore.kernel.org/linux-trace-kernel/20240516133454.681ba6a0@rorschach.local.home

Cc: Masami Hiramatsu &lt;mhiramat@kernel.org&gt;
Cc: Mathieu Desnoyers &lt;mathieu.desnoyers@efficios.com&gt;
Cc: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
Cc: Julia Lawall &lt;Julia.Lawall@inria.fr&gt;
Signed-off-by: Steven Rostedt (Google) &lt;rostedt@goodmis.org&gt;
Acked-by: Jani Nikula &lt;jani.nikula@intel.com&gt;
Acked-by: Christian König &lt;christian.koenig@amd.com&gt; for the amdgpu parts.
Acked-by: Thomas Hellström &lt;thomas.hellstrom@linux.intel.com&gt; #for
Acked-by: Rafael J. Wysocki &lt;rafael@kernel.org&gt; # for thermal
Acked-by: Takashi Iwai &lt;tiwai@suse.de&gt;
Acked-by: Darrick J. Wong &lt;djwong@kernel.org&gt;	# xfs
Tested-by: Guenter Roeck &lt;linux@roeck-us.net&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
With the rework of how the __string() handles dynamic strings where it
saves off the source string in field in the helper structure[1], the
assignment of that value to the trace event field is stored in the helper
value and does not need to be passed in again.

This means that with:

  __string(field, mystring)

Which use to be assigned with __assign_str(field, mystring), no longer
needs the second parameter and it is unused. With this, __assign_str()
will now only get a single parameter.

There's over 700 users of __assign_str() and because coccinelle does not
handle the TRACE_EVENT() macro I ended up using the following sed script:

  git grep -l __assign_str | while read a ; do
      sed -e 's/\(__assign_str([^,]*[^ ,]\) *,[^;]*/\1)/' $a &gt; /tmp/test-file;
      mv /tmp/test-file $a;
  done

I then searched for __assign_str() that did not end with ';' as those
were multi line assignments that the sed script above would fail to catch.

Note, the same updates will need to be done for:

  __assign_str_len()
  __assign_rel_str()
  __assign_rel_str_len()

I tested this with both an allmodconfig and an allyesconfig (build only for both).

[1] https://lore.kernel.org/linux-trace-kernel/20240222211442.634192653@goodmis.org/

Link: https://lore.kernel.org/linux-trace-kernel/20240516133454.681ba6a0@rorschach.local.home

Cc: Masami Hiramatsu &lt;mhiramat@kernel.org&gt;
Cc: Mathieu Desnoyers &lt;mathieu.desnoyers@efficios.com&gt;
Cc: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
Cc: Julia Lawall &lt;Julia.Lawall@inria.fr&gt;
Signed-off-by: Steven Rostedt (Google) &lt;rostedt@goodmis.org&gt;
Acked-by: Jani Nikula &lt;jani.nikula@intel.com&gt;
Acked-by: Christian König &lt;christian.koenig@amd.com&gt; for the amdgpu parts.
Acked-by: Thomas Hellström &lt;thomas.hellstrom@linux.intel.com&gt; #for
Acked-by: Rafael J. Wysocki &lt;rafael@kernel.org&gt; # for thermal
Acked-by: Takashi Iwai &lt;tiwai@suse.de&gt;
Acked-by: Darrick J. Wong &lt;djwong@kernel.org&gt;	# xfs
Tested-by: Guenter Roeck &lt;linux@roeck-us.net&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>net: change proto and proto_ops accept type</title>
<updated>2024-05-14T00:19:09+00:00</updated>
<author>
<name>Jens Axboe</name>
<email>axboe@kernel.dk</email>
</author>
<published>2024-05-09T15:20:08+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=92ef0fd55ac80dfc2e4654edfe5d1ddfa6e070fe'/>
<id>92ef0fd55ac80dfc2e4654edfe5d1ddfa6e070fe</id>
<content type='text'>
Rather than pass in flags, error pointer, and whether this is a kernel
invocation or not, add a struct proto_accept_arg struct as the argument.
This then holds all of these arguments, and prepares accept for being
able to pass back more information.

No functional changes in this patch.

Acked-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Rather than pass in flags, error pointer, and whether this is a kernel
invocation or not, add a struct proto_accept_arg struct as the argument.
This then holds all of these arguments, and prepares accept for being
able to pass back more information.

No functional changes in this patch.

Acked-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net</title>
<updated>2024-05-09T17:01:01+00:00</updated>
<author>
<name>Jakub Kicinski</name>
<email>kuba@kernel.org</email>
</author>
<published>2024-05-09T16:59:29+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=e7073830cc8b52ef3df7dd150e4dac7706e0e104'/>
<id>e7073830cc8b52ef3df7dd150e4dac7706e0e104</id>
<content type='text'>
Cross-merge networking fixes after downstream PR.

No conflicts.

Adjacent changes:

drivers/net/ethernet/hisilicon/hns3/hns3pf/hclge_main.c
  35d92abfbad8 ("net: hns3: fix kernel crash when devlink reload during initialization")
  2a1a1a7b5fd7 ("net: hns3: add command queue trace for hns3")

Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Cross-merge networking fixes after downstream PR.

No conflicts.

Adjacent changes:

drivers/net/ethernet/hisilicon/hns3/hns3pf/hclge_main.c
  35d92abfbad8 ("net: hns3: fix kernel crash when devlink reload during initialization")
  2a1a1a7b5fd7 ("net: hns3: add command queue trace for hns3")

Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>net/smc: fix neighbour and rtable leak in smc_ib_find_route()</title>
<updated>2024-05-09T08:03:43+00:00</updated>
<author>
<name>Wen Gu</name>
<email>guwen@linux.alibaba.com</email>
</author>
<published>2024-05-07T12:53:31+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=2ddc0dd7fec86ee53b8928a5cca5fbddd4fc7c06'/>
<id>2ddc0dd7fec86ee53b8928a5cca5fbddd4fc7c06</id>
<content type='text'>
In smc_ib_find_route(), the neighbour found by neigh_lookup() and rtable
resolved by ip_route_output_flow() are not released or put before return.
It may cause the refcount leak, so fix it.

Link: https://lore.kernel.org/r/20240506015439.108739-1-guwen@linux.alibaba.com
Fixes: e5c4744cfb59 ("net/smc: add SMC-Rv2 connection establishment")
Signed-off-by: Wen Gu &lt;guwen@linux.alibaba.com&gt;
Link: https://lore.kernel.org/r/20240507125331.2808-1-guwen@linux.alibaba.com
Signed-off-by: Paolo Abeni &lt;pabeni@redhat.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
In smc_ib_find_route(), the neighbour found by neigh_lookup() and rtable
resolved by ip_route_output_flow() are not released or put before return.
It may cause the refcount leak, so fix it.

Link: https://lore.kernel.org/r/20240506015439.108739-1-guwen@linux.alibaba.com
Fixes: e5c4744cfb59 ("net/smc: add SMC-Rv2 connection establishment")
Signed-off-by: Wen Gu &lt;guwen@linux.alibaba.com&gt;
Link: https://lore.kernel.org/r/20240507125331.2808-1-guwen@linux.alibaba.com
Signed-off-by: Paolo Abeni &lt;pabeni@redhat.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>net: Remove ctl_table sentinel elements from several networking subsystems</title>
<updated>2024-05-03T12:29:42+00:00</updated>
<author>
<name>Joel Granados</name>
<email>j.granados@samsung.com</email>
</author>
<published>2024-05-01T09:29:29+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=73dbd8cf7947f7da47b23f4adc07593c4dc452b4'/>
<id>73dbd8cf7947f7da47b23f4adc07593c4dc452b4</id>
<content type='text'>
This commit comes at the tail end of a greater effort to remove the
empty elements at the end of the ctl_table arrays (sentinels) which
will reduce the overall build time size of the kernel and run time
memory bloat by ~64 bytes per sentinel (further information Link :
https://lore.kernel.org/all/ZO5Yx5JFogGi%2FcBo@bombadil.infradead.org/)

To avoid lots of small commits, this commit brings together network
changes from (as they appear in MAINTAINERS) LLC, MPTCP, NETROM NETWORK
LAYER, PHONET PROTOCOL, ROSE NETWORK LAYER, RXRPC SOCKETS, SCTP
PROTOCOL, SHARED MEMORY COMMUNICATIONS (SMC), TIPC NETWORK LAYER and
NETWORKING [IPSEC]

* Remove sentinel element from ctl_table structs.
* Replace empty array registration with the register_net_sysctl_sz call
  in llc_sysctl_init
* Replace the for loop stop condition that tests for procname == NULL
  with one that depends on array size in sctp_sysctl_net_register
* Remove instances where an array element is zeroed out to make it look
  like a sentinel in xfrm_sysctl_init. This is not longer needed and is
  safe after commit c899710fe7f9 ("networking: Update to
  register_net_sysctl_sz") added the array size to the ctl_table
  registration
* Use a table_size variable to keep the value of ARRAY_SIZE

Signed-off-by: Joel Granados &lt;j.granados@samsung.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
This commit comes at the tail end of a greater effort to remove the
empty elements at the end of the ctl_table arrays (sentinels) which
will reduce the overall build time size of the kernel and run time
memory bloat by ~64 bytes per sentinel (further information Link :
https://lore.kernel.org/all/ZO5Yx5JFogGi%2FcBo@bombadil.infradead.org/)

To avoid lots of small commits, this commit brings together network
changes from (as they appear in MAINTAINERS) LLC, MPTCP, NETROM NETWORK
LAYER, PHONET PROTOCOL, ROSE NETWORK LAYER, RXRPC SOCKETS, SCTP
PROTOCOL, SHARED MEMORY COMMUNICATIONS (SMC), TIPC NETWORK LAYER and
NETWORKING [IPSEC]

* Remove sentinel element from ctl_table structs.
* Replace empty array registration with the register_net_sysctl_sz call
  in llc_sysctl_init
* Replace the for loop stop condition that tests for procname == NULL
  with one that depends on array size in sctp_sysctl_net_register
* Remove instances where an array element is zeroed out to make it look
  like a sentinel in xfrm_sysctl_init. This is not longer needed and is
  safe after commit c899710fe7f9 ("networking: Update to
  register_net_sysctl_sz") added the array size to the ctl_table
  registration
* Use a table_size variable to keep the value of ARRAY_SIZE

Signed-off-by: Joel Granados &lt;j.granados@samsung.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>net/smc: implement DMB-merged operations of loopback-ism</title>
<updated>2024-04-30T11:24:49+00:00</updated>
<author>
<name>Wen Gu</name>
<email>guwen@linux.alibaba.com</email>
</author>
<published>2024-04-28T06:07:38+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=c3a910f2380fe294d14e42af66af3d3eed8fecbf'/>
<id>c3a910f2380fe294d14e42af66af3d3eed8fecbf</id>
<content type='text'>
This implements operations related to merging sndbuf with peer DMB in
loopback-ism. The DMB won't be freed until no sndbuf is attached to it.

Signed-off-by: Wen Gu &lt;guwen@linux.alibaba.com&gt;
Reviewed-by: Wenjia Zhang &lt;wenjia@linux.ibm.com&gt;
Reviewed-and-tested-by: Jan Karcher &lt;jaka@linux.ibm.com&gt;
Signed-off-by: Paolo Abeni &lt;pabeni@redhat.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
This implements operations related to merging sndbuf with peer DMB in
loopback-ism. The DMB won't be freed until no sndbuf is attached to it.

Signed-off-by: Wen Gu &lt;guwen@linux.alibaba.com&gt;
Reviewed-by: Wenjia Zhang &lt;wenjia@linux.ibm.com&gt;
Reviewed-and-tested-by: Jan Karcher &lt;jaka@linux.ibm.com&gt;
Signed-off-by: Paolo Abeni &lt;pabeni@redhat.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>net/smc: adapt cursor update when sndbuf and peer DMB are merged</title>
<updated>2024-04-30T11:24:48+00:00</updated>
<author>
<name>Wen Gu</name>
<email>guwen@linux.alibaba.com</email>
</author>
<published>2024-04-28T06:07:37+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=cc0ab806fc52e77f961b275ebb58024bd0e7adf2'/>
<id>cc0ab806fc52e77f961b275ebb58024bd0e7adf2</id>
<content type='text'>
If the local sndbuf shares the same physical memory with peer DMB,
the cursor update processing needs to be adapted to ensure that the
data to be consumed won't be overwritten.

So in this case, the fin_curs and sndbuf_space that were originally
updated after sending the CDC message should be modified to not be
update until the peer updates cons_curs.

Signed-off-by: Wen Gu &lt;guwen@linux.alibaba.com&gt;
Reviewed-by: Wenjia Zhang &lt;wenjia@linux.ibm.com&gt;
Reviewed-and-tested-by: Jan Karcher &lt;jaka@linux.ibm.com&gt;
Signed-off-by: Paolo Abeni &lt;pabeni@redhat.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
If the local sndbuf shares the same physical memory with peer DMB,
the cursor update processing needs to be adapted to ensure that the
data to be consumed won't be overwritten.

So in this case, the fin_curs and sndbuf_space that were originally
updated after sending the CDC message should be modified to not be
update until the peer updates cons_curs.

Signed-off-by: Wen Gu &lt;guwen@linux.alibaba.com&gt;
Reviewed-by: Wenjia Zhang &lt;wenjia@linux.ibm.com&gt;
Reviewed-and-tested-by: Jan Karcher &lt;jaka@linux.ibm.com&gt;
Signed-off-by: Paolo Abeni &lt;pabeni@redhat.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>net/smc: {at|de}tach sndbuf to peer DMB if supported</title>
<updated>2024-04-30T11:24:48+00:00</updated>
<author>
<name>Wen Gu</name>
<email>guwen@linux.alibaba.com</email>
</author>
<published>2024-04-28T06:07:36+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=ae2be35cbed2c8385e890147ea321a3fcc3ca5fa'/>
<id>ae2be35cbed2c8385e890147ea321a3fcc3ca5fa</id>
<content type='text'>
If the device used by SMC-D supports merging local sndbuf to peer DMB,
then create sndbuf descriptor and attach it to peer DMB once peer
token is obtained, and detach and free the sndbuf descriptor when the
connection is freed.

Signed-off-by: Wen Gu &lt;guwen@linux.alibaba.com&gt;
Reviewed-by: Wenjia Zhang &lt;wenjia@linux.ibm.com&gt;
Reviewed-and-tested-by: Jan Karcher &lt;jaka@linux.ibm.com&gt;
Signed-off-by: Paolo Abeni &lt;pabeni@redhat.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
If the device used by SMC-D supports merging local sndbuf to peer DMB,
then create sndbuf descriptor and attach it to peer DMB once peer
token is obtained, and detach and free the sndbuf descriptor when the
connection is freed.

Signed-off-by: Wen Gu &lt;guwen@linux.alibaba.com&gt;
Reviewed-by: Wenjia Zhang &lt;wenjia@linux.ibm.com&gt;
Reviewed-and-tested-by: Jan Karcher &lt;jaka@linux.ibm.com&gt;
Signed-off-by: Paolo Abeni &lt;pabeni@redhat.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>net/smc: add operations to merge sndbuf with peer DMB</title>
<updated>2024-04-30T11:24:48+00:00</updated>
<author>
<name>Wen Gu</name>
<email>guwen@linux.alibaba.com</email>
</author>
<published>2024-04-28T06:07:35+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=4398888268582cb51b69c6ee94f551bb8d37d12f'/>
<id>4398888268582cb51b69c6ee94f551bb8d37d12f</id>
<content type='text'>
In some scenarios using Emulated-ISM device, sndbuf can share the same
physical memory region with peer DMB to avoid data copy from one side
to the other. In such case the sndbuf is only a descriptor that
describes the shared memory and does not actually occupy memory, it's
more like a ghost buffer.

      +----------+                     +----------+
      | socket A |                     | socket B |
      +----------+                     +----------+
            |                               |
       +--------+                       +--------+
       | sndbuf |                       |  DMB   |
       |  desc  |                       |  desc  |
       +--------+                       +--------+
            |                               |
            |                          +----v-----+
            +--------------------------&gt;  memory  |
                                       +----------+

So here introduces three new SMC-D device operations to check if this
feature is supported by device, and to {attach|detach} ghost sndbuf to
peer DMB. For now only loopback-ism supports this.

Signed-off-by: Wen Gu &lt;guwen@linux.alibaba.com&gt;
Reviewed-by: Wenjia Zhang &lt;wenjia@linux.ibm.com&gt;
Reviewed-and-tested-by: Jan Karcher &lt;jaka@linux.ibm.com&gt;
Signed-off-by: Paolo Abeni &lt;pabeni@redhat.com&gt;
</content>
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<pre>
In some scenarios using Emulated-ISM device, sndbuf can share the same
physical memory region with peer DMB to avoid data copy from one side
to the other. In such case the sndbuf is only a descriptor that
describes the shared memory and does not actually occupy memory, it's
more like a ghost buffer.

      +----------+                     +----------+
      | socket A |                     | socket B |
      +----------+                     +----------+
            |                               |
       +--------+                       +--------+
       | sndbuf |                       |  DMB   |
       |  desc  |                       |  desc  |
       +--------+                       +--------+
            |                               |
            |                          +----v-----+
            +--------------------------&gt;  memory  |
                                       +----------+

So here introduces three new SMC-D device operations to check if this
feature is supported by device, and to {attach|detach} ghost sndbuf to
peer DMB. For now only loopback-ism supports this.

Signed-off-by: Wen Gu &lt;guwen@linux.alibaba.com&gt;
Reviewed-by: Wenjia Zhang &lt;wenjia@linux.ibm.com&gt;
Reviewed-and-tested-by: Jan Karcher &lt;jaka@linux.ibm.com&gt;
Signed-off-by: Paolo Abeni &lt;pabeni@redhat.com&gt;
</pre>
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</content>
</entry>
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