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| author | Chuck Lever <cel@kernel.org> | 2026-08-28 09:50:36 -0400 |
|---|---|---|
| committer | Chuck Lever <cel@kernel.org> | 2026-10-04 21:15:29 -0400 |
| commit | bde744fe9f2ede72b38985a24b459f649e8ed5fa (patch) | |
| tree | 434ab018c30c289985210c04c9ab8083727097ea /include | |
| parent | 46913d461a351e0dd09ab4344c73c73f4d34ff64 (diff) | |
| download | linux-next-bde744fe9f2ede72b38985a24b459f649e8ed5fa.tar.gz linux-next-bde744fe9f2ede72b38985a24b459f649e8ed5fa.zip | |
SUNRPC: Skip xpt_reserved accounting for non-UDP transports
The xpt_reserved counter exists for UDP socket-buffer back-pressure.
svc_udp_has_wspace() is the only has_wspace implementation that
consults it, so on TCP and RDMA the counter is maintained and never
read. svc_handle_xprt() adds to it once per RPC. svc_reserve()
shrinks it again on each call from svc_process_common(), from
svc_xprt_release(), and from each proc function that calls
svc_reserve_auth(). Every shrinking call also runs
svc_xprt_resource_released(), which issues an smp_mb() and can
enqueue the transport.
Add an xcl_flags field to svc_xprt_class and set
SVC_XPRT_FLAG_WSPACE_RESERVE on the UDP class. Gate the xpt_reserved
accounting on that flag.
After the change, svc_reserve() no longer calls
svc_xprt_resource_released() on TCP and RDMA. Two paths still cover
that enqueue. svc_xprt_release() reaches the helper through
svc_xprt_release_slot(), and svc_xprt_received() enqueues a transport
whose XPT_DATA remains set.
Link: https://patch.msgid.link/20260828135036.796842-4-cel@kernel.org
Signed-off-by: Chuck Lever <cel@kernel.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/sunrpc/svc_xprt.h | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/include/linux/sunrpc/svc_xprt.h b/include/linux/sunrpc/svc_xprt.h index da2a2531e110..2af222f3ea2c 100644 --- a/include/linux/sunrpc/svc_xprt.h +++ b/include/linux/sunrpc/svc_xprt.h @@ -37,6 +37,9 @@ struct svc_xprt_class { struct list_head xcl_list; u32 xcl_max_payload; int xcl_ident; + u32 xcl_flags; +/* Set only on classes whose xpo_has_wspace() reads xpt_reserved */ +#define SVC_XPRT_FLAG_WSPACE_RESERVE BIT(0) }; /* @@ -59,7 +62,7 @@ struct svc_xprt { unsigned long xpt_flags; struct svc_serv *xpt_server; /* service for transport */ - atomic_t xpt_reserved; /* space on outq that is rsvd */ + atomic_t xpt_reserved; /* outq space rsvd, UDP only */ atomic_t xpt_nr_rqsts; /* Number of requests */ struct mutex xpt_mutex; /* to serialize sending data */ spinlock_t xpt_lock; /* protects sk_deferred |