linux.git/net/rds/message.c, branch v4.20

net/rds: remove user triggered WARN_ON in rds_sendmsg

2018-12-19T18:27:58+00:00

per comment from Leon in rdma mailing list
https://lkml.org/lkml/2018/10/31/312 :

Please don't forget to remove user triggered WARN_ON.
https://lwn.net/Articles/769365/
"Greg Kroah-Hartman raised the problem of core kernel API code that will
use WARN_ON_ONCE() to complain about bad usage; that will not generate
the desired result if WARN_ON_ONCE() is configured to crash the machine.
He was told that the code should just call pr_warn() instead, and that
the called function should return an error in such situations. It was
generally agreed that any WARN_ON() or WARN_ON_ONCE() calls that can be
triggered from user space need to be fixed."

in addition harden rds_sendmsg to detect and overcome issues with
invalid sg count and fail the sendmsg.

Suggested-by: Leon Romanovsky 
Acked-by: Santosh Shilimkar 
Signed-off-by: shamir rabinovitch 
Signed-off-by: David S. Miller

rds: remove trailing whitespace and blank lines

2018-07-24T21:10:42+00:00

Signed-off-by: Stephen Hemminger 
Signed-off-by: David S. Miller

rds: remove redundant variable 'sg_off'

2018-03-12T15:12:38+00:00

Variable sg_off is assigned a value but it is never read, hence it is
redundant and can be removed.

Cleans up clang warning:
net/rds/message.c:373:2: warning: Value stored to 'sg_off' is never read

Signed-off-by: Colin Ian King 
Acked-by: Sowmini Varadhan 
Acked-by: Santosh Shilimkar 
Signed-off-by: David S. Miller

rds: rds_info_from_znotifier() can be static

2018-03-09T02:54:00+00:00

Fixes: 9426bbc6de99 ("rds: use list structure to track information for zerocopy completion notification")
Signed-off-by: Fengguang Wu 
Signed-off-by: David S. Miller

rds: rds_message_zcopy_from_user() can be static

2018-03-09T02:52:20+00:00

Fixes: d40a126b16ea ("rds: refactor zcopy code into rds_message_zcopy_from_user")
Signed-off-by: Fengguang Wu 
Acked-by: Sowmini Varadhan 
Signed-off-by: David S. Miller

rds: use list structure to track information for zerocopy completion notification

2018-03-07T23:05:57+00:00

Commit 401910db4cd4 ("rds: deliver zerocopy completion notification
with data") removes support fo r zerocopy completion notification
on the sk_error_queue, thus we no longer need to track the cookie
information in sk_buff structures.

This commit removes the struct sk_buff_head rs_zcookie_queue by
a simpler list that results in a smaller memory footprint as well
as more efficient memory_allocation time.

Signed-off-by: Sowmini Varadhan 
Acked-by: Willem de Bruijn 
Signed-off-by: David S. Miller

rds: refactor zcopy code into rds_message_zcopy_from_user

2018-03-07T23:05:57+00:00

Move the large block of code predicated on zcopy from
rds_message_copy_from_user into a new function,
rds_message_zcopy_from_user()

Signed-off-by: Sowmini Varadhan 
Acked-by: Willem de Bruijn 
Signed-off-by: David S. Miller

rds: deliver zerocopy completion notification with data

2018-02-27T19:19:11+00:00

This commit is an optimization over commit 01883eda72bd
("rds: support for zcopy completion notification") for PF_RDS sockets.

RDS applications are predominantly request-response transactions, so
it is more efficient to reduce the number of system calls and have
zerocopy completion notification delivered as ancillary data on the
POLLIN channel.

Cookies are passed up as ancillary data (at level SOL_RDS) in a
struct rds_zcopy_cookies when the returned value of recvmsg() is
greater than, or equal to, 0. A max of RDS_MAX_ZCOOKIES may be passed
with each message.

This commit removes support for zerocopy completion notification on
MSG_ERRQUEUE for PF_RDS sockets.

Signed-off-by: Sowmini Varadhan 
Acked-by: Willem de Bruijn 
Acked-by: Santosh Shilimkar 
Signed-off-by: David S. Miller

rds: zerocopy Tx support.

2018-02-16T21:04:17+00:00

If the MSG_ZEROCOPY flag is specified with rds_sendmsg(), and,
if the SO_ZEROCOPY socket option has been set on the PF_RDS socket,
application pages sent down with rds_sendmsg() are pinned.

The pinning uses the accounting infrastructure added by
Commit a91dbff551a6 ("sock: ulimit on MSG_ZEROCOPY pages")

The payload bytes in the message may not be modified for the
duration that the message has been pinned. A multi-threaded
application using this infrastructure may thus need to be notified
about send-completion so that it can free/reuse the buffers
passed to rds_sendmsg(). Notification of send-completion will
identify each message-buffer by a cookie that the application
must specify as ancillary data to rds_sendmsg().
The ancillary data in this case has cmsg_level == SOL_RDS
and cmsg_type == RDS_CMSG_ZCOPY_COOKIE.

Signed-off-by: Sowmini Varadhan 
Acked-by: Santosh Shilimkar 
Acked-by: Willem de Bruijn 
Signed-off-by: David S. Miller

rds: support for zcopy completion notification

2018-02-16T21:04:17+00:00

RDS removes a datagram (rds_message) from the retransmit queue when
an ACK is received. The ACK indicates that the receiver has queued
the RDS datagram, so that the sender can safely forget the datagram.
When all references to the rds_message are quiesced, rds_message_purge
is called to release resources used by the rds_message

If the datagram to be removed had pinned pages set up, add
an entry to the rs->rs_znotify_queue so that the notifcation
will be sent up via rds_rm_zerocopy_callback() when the
rds_message is eventually freed by rds_message_purge.

rds_rm_zerocopy_callback() attempts to batch the number of cookies
sent with each notification  to a max of SO_EE_ORIGIN_MAX_ZCOOKIES.
This is achieved by checking the tail skb in the sk_error_queue:
if this has room for one more cookie, the cookie from the
current notification is added; else a new skb is added to the
sk_error_queue. Every invocation of rds_rm_zerocopy_callback() will
trigger a ->sk_error_report to notify the application.

Signed-off-by: Sowmini Varadhan 
Acked-by: Santosh Shilimkar 
Acked-by: Willem de Bruijn 
Signed-off-by: David S. Miller