Commit 5c507329 authored by Pedro Tammela's avatar Pedro Tammela Committed by Andrii Nakryiko
Browse files

libbpf: Clarify flags in ringbuf helpers 



In 'bpf_ringbuf_reserve()' we require the flag to '0' at the moment.

For 'bpf_ringbuf_{discard,submit,output}' a flag of '0' might send a
notification to the process if needed.

Signed-off-by: default avatarPedro Tammela <pctammela@mojatatu.com>
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210412192434.944343-1-pctammela@mojatatu.com
parent aadb2bb8

include/uapi/linux/bpf.h

+16 −0
Original line number Diff line number Diff line
@@ -4082,12 +4082,20 @@ union bpf_attr { 
 * 		of new data availability is sent.

 * 		If **BPF_RB_FORCE_WAKEUP** is specified in *flags*, notification

 * 		of new data availability is sent unconditionally.

 * 		If **0** is specified in *flags*, an adaptive notification

 * 		of new data availability is sent.

 *

 * 		An adaptive notification is a notification sent whenever the user-space

 * 		process has caught up and consumed all available payloads. In case the user-space

 * 		process is still processing a previous payload, then no notification is needed

 * 		as it will process the newly added payload automatically.

 * 	Return

 * 		0 on success, or a negative error in case of failure.

 *

 * void *bpf_ringbuf_reserve(void *ringbuf, u64 size, u64 flags)

 * 	Description

 * 		Reserve *size* bytes of payload in a ring buffer *ringbuf*.

 * 		*flags* must be 0.

 * 	Return

 * 		Valid pointer with *size* bytes of memory available; NULL,

 * 		otherwise.
@@ -4099,6 +4107,10 @@ union bpf_attr { 
 * 		of new data availability is sent.

 * 		If **BPF_RB_FORCE_WAKEUP** is specified in *flags*, notification

 * 		of new data availability is sent unconditionally.

 * 		If **0** is specified in *flags*, an adaptive notification

 * 		of new data availability is sent.

 *

 * 		See 'bpf_ringbuf_output()' for the definition of adaptive notification.

 * 	Return

 * 		Nothing. Always succeeds.

 *
@@ -4109,6 +4121,10 @@ union bpf_attr { 
 * 		of new data availability is sent.

 * 		If **BPF_RB_FORCE_WAKEUP** is specified in *flags*, notification

 * 		of new data availability is sent unconditionally.

 * 		If **0** is specified in *flags*, an adaptive notification

 * 		of new data availability is sent.

 *

 * 		See 'bpf_ringbuf_output()' for the definition of adaptive notification.

 * 	Return

 * 		Nothing. Always succeeds.

 *

tools/include/uapi/linux/bpf.h

+16 −0
Original line number Diff line number Diff line
@@ -4082,12 +4082,20 @@ union bpf_attr { 
 * 		of new data availability is sent.

 * 		If **BPF_RB_FORCE_WAKEUP** is specified in *flags*, notification

 * 		of new data availability is sent unconditionally.

 * 		If **0** is specified in *flags*, an adaptive notification

 * 		of new data availability is sent.

 *

 * 		An adaptive notification is a notification sent whenever the user-space

 * 		process has caught up and consumed all available payloads. In case the user-space

 * 		process is still processing a previous payload, then no notification is needed

 * 		as it will process the newly added payload automatically.

 * 	Return

 * 		0 on success, or a negative error in case of failure.

 *

 * void *bpf_ringbuf_reserve(void *ringbuf, u64 size, u64 flags)

 * 	Description

 * 		Reserve *size* bytes of payload in a ring buffer *ringbuf*.

 * 		*flags* must be 0.

 * 	Return

 * 		Valid pointer with *size* bytes of memory available; NULL,

 * 		otherwise.
@@ -4099,6 +4107,10 @@ union bpf_attr { 
 * 		of new data availability is sent.

 * 		If **BPF_RB_FORCE_WAKEUP** is specified in *flags*, notification

 * 		of new data availability is sent unconditionally.

 * 		If **0** is specified in *flags*, an adaptive notification

 * 		of new data availability is sent.

 *

 * 		See 'bpf_ringbuf_output()' for the definition of adaptive notification.

 * 	Return

 * 		Nothing. Always succeeds.

 *
@@ -4109,6 +4121,10 @@ union bpf_attr { 
 * 		of new data availability is sent.

 * 		If **BPF_RB_FORCE_WAKEUP** is specified in *flags*, notification

 * 		of new data availability is sent unconditionally.

 * 		If **0** is specified in *flags*, an adaptive notification

 * 		of new data availability is sent.

 *

 * 		See 'bpf_ringbuf_output()' for the definition of adaptive notification.

 * 	Return

 * 		Nothing. Always succeeds.

 *