* [PATCH bpf-next 0/4] Fix perf_buffer creation on systems with offline CPUs @ 2019-12-12 1:35 Andrii Nakryiko 2019-12-13 21:04 ` Alexei Starovoitov ` (2 more replies) 0 siblings, 3 replies; 9+ messages in thread From: Andrii Nakryiko @ 2019-12-12 1:35 UTC (permalink / raw) To: bpf, netdev, ast, daniel; +Cc: andrii.nakryiko, kernel-team, Andrii Nakryiko This patch set fixes perf_buffer__new() behavior on systems which have some of the CPUs offline/missing (due to difference between "possible" and "online" sets). perf_buffer will create per-CPU buffer and open/attach to corresponding perf_event only on CPUs present and online at the moment of perf_buffer creation. Without this logic, perf_buffer creation has no chances of succeeding on such systems, preventing valid and correct BPF applications from starting. Andrii Nakryiko (4): libbpf: extract and generalize CPU mask parsing logic selftests/bpf: add CPU mask parsing tests libbpf: don't attach perf_buffer to offline/missing CPUs selftests/bpf: fix perf_buffer test on systems w/ offline CPUs tools/lib/bpf/libbpf.c | 157 ++++++++++++------ tools/lib/bpf/libbpf_internal.h | 2 + .../selftests/bpf/prog_tests/cpu_mask.c | 78 +++++++++ .../selftests/bpf/prog_tests/perf_buffer.c | 29 +++- 4 files changed, 213 insertions(+), 53 deletions(-) create mode 100644 tools/testing/selftests/bpf/prog_tests/cpu_mask.c -- 2.17.1 ^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH bpf-next 0/4] Fix perf_buffer creation on systems with offline CPUs 2019-12-12 1:35 [PATCH bpf-next 0/4] Fix perf_buffer creation on systems with offline CPUs Andrii Nakryiko @ 2019-12-13 21:04 ` Alexei Starovoitov 2019-12-16 14:44 ` Daniel Borkmann 2020-02-09 17:18 ` Naresh Kamboju 2 siblings, 0 replies; 9+ messages in thread From: Alexei Starovoitov @ 2019-12-13 21:04 UTC (permalink / raw) To: Andrii Nakryiko Cc: bpf, Network Development, Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Kernel Team On Wed, Dec 11, 2019 at 5:35 PM Andrii Nakryiko <andriin@fb.com> wrote: > > This patch set fixes perf_buffer__new() behavior on systems which have some of > the CPUs offline/missing (due to difference between "possible" and "online" > sets). perf_buffer will create per-CPU buffer and open/attach to corresponding > perf_event only on CPUs present and online at the moment of perf_buffer > creation. Without this logic, perf_buffer creation has no chances of > succeeding on such systems, preventing valid and correct BPF applications from > starting. Applied. Thanks ^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH bpf-next 0/4] Fix perf_buffer creation on systems with offline CPUs 2019-12-12 1:35 [PATCH bpf-next 0/4] Fix perf_buffer creation on systems with offline CPUs Andrii Nakryiko 2019-12-13 21:04 ` Alexei Starovoitov @ 2019-12-16 14:44 ` Daniel Borkmann 2019-12-16 17:59 ` Andrii Nakryiko 2020-02-09 17:18 ` Naresh Kamboju 2 siblings, 1 reply; 9+ messages in thread From: Daniel Borkmann @ 2019-12-16 14:44 UTC (permalink / raw) To: Andrii Nakryiko; +Cc: bpf, netdev, ast, andrii.nakryiko, kernel-team On Wed, Dec 11, 2019 at 05:35:20PM -0800, Andrii Nakryiko wrote: > This patch set fixes perf_buffer__new() behavior on systems which have some of > the CPUs offline/missing (due to difference between "possible" and "online" > sets). perf_buffer will create per-CPU buffer and open/attach to corresponding > perf_event only on CPUs present and online at the moment of perf_buffer > creation. Without this logic, perf_buffer creation has no chances of > succeeding on such systems, preventing valid and correct BPF applications from > starting. Once CPU goes back online and processes BPF events, any attempt to push into perf RB via bpf_perf_event_output() with flag BPF_F_CURRENT_CPU would silently get discarded. Should rather perf API be fixed instead of plain skipping as done here to at least allow creation of ring buffer for BPF to avoid such case? > Andrii Nakryiko (4): > libbpf: extract and generalize CPU mask parsing logic > selftests/bpf: add CPU mask parsing tests > libbpf: don't attach perf_buffer to offline/missing CPUs > selftests/bpf: fix perf_buffer test on systems w/ offline CPUs > > tools/lib/bpf/libbpf.c | 157 ++++++++++++------ > tools/lib/bpf/libbpf_internal.h | 2 + > .../selftests/bpf/prog_tests/cpu_mask.c | 78 +++++++++ > .../selftests/bpf/prog_tests/perf_buffer.c | 29 +++- > 4 files changed, 213 insertions(+), 53 deletions(-) > create mode 100644 tools/testing/selftests/bpf/prog_tests/cpu_mask.c > > -- > 2.17.1 > ^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH bpf-next 0/4] Fix perf_buffer creation on systems with offline CPUs 2019-12-16 14:44 ` Daniel Borkmann @ 2019-12-16 17:59 ` Andrii Nakryiko 2019-12-17 13:00 ` Daniel Borkmann 0 siblings, 1 reply; 9+ messages in thread From: Andrii Nakryiko @ 2019-12-16 17:59 UTC (permalink / raw) To: Daniel Borkmann Cc: Andrii Nakryiko, bpf, Networking, Alexei Starovoitov, Kernel Team On Mon, Dec 16, 2019 at 6:44 AM Daniel Borkmann <daniel@iogearbox.net> wrote: > > On Wed, Dec 11, 2019 at 05:35:20PM -0800, Andrii Nakryiko wrote: > > This patch set fixes perf_buffer__new() behavior on systems which have some of > > the CPUs offline/missing (due to difference between "possible" and "online" > > sets). perf_buffer will create per-CPU buffer and open/attach to corresponding > > perf_event only on CPUs present and online at the moment of perf_buffer > > creation. Without this logic, perf_buffer creation has no chances of > > succeeding on such systems, preventing valid and correct BPF applications from > > starting. > > Once CPU goes back online and processes BPF events, any attempt to push into > perf RB via bpf_perf_event_output() with flag BPF_F_CURRENT_CPU would silently bpf_perf_event_output() will return error code in such case, so it's not exactly undetectable by application. > get discarded. Should rather perf API be fixed instead of plain skipping as done > here to at least allow creation of ring buffer for BPF to avoid such case? Can you elaborate on what perf API fix you have in mind? Do you mean for perf to allow attaching ring buffer to offline CPU or something else? > > > Andrii Nakryiko (4): > > libbpf: extract and generalize CPU mask parsing logic > > selftests/bpf: add CPU mask parsing tests > > libbpf: don't attach perf_buffer to offline/missing CPUs > > selftests/bpf: fix perf_buffer test on systems w/ offline CPUs > > > > tools/lib/bpf/libbpf.c | 157 ++++++++++++------ > > tools/lib/bpf/libbpf_internal.h | 2 + > > .../selftests/bpf/prog_tests/cpu_mask.c | 78 +++++++++ > > .../selftests/bpf/prog_tests/perf_buffer.c | 29 +++- > > 4 files changed, 213 insertions(+), 53 deletions(-) > > create mode 100644 tools/testing/selftests/bpf/prog_tests/cpu_mask.c > > > > -- > > 2.17.1 > > ^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH bpf-next 0/4] Fix perf_buffer creation on systems with offline CPUs 2019-12-16 17:59 ` Andrii Nakryiko @ 2019-12-17 13:00 ` Daniel Borkmann 2019-12-20 17:46 ` Andrii Nakryiko 0 siblings, 1 reply; 9+ messages in thread From: Daniel Borkmann @ 2019-12-17 13:00 UTC (permalink / raw) To: Andrii Nakryiko Cc: Andrii Nakryiko, bpf, Networking, Alexei Starovoitov, Kernel Team On 12/16/19 6:59 PM, Andrii Nakryiko wrote: > On Mon, Dec 16, 2019 at 6:44 AM Daniel Borkmann <daniel@iogearbox.net> wrote: >> On Wed, Dec 11, 2019 at 05:35:20PM -0800, Andrii Nakryiko wrote: >>> This patch set fixes perf_buffer__new() behavior on systems which have some of >>> the CPUs offline/missing (due to difference between "possible" and "online" >>> sets). perf_buffer will create per-CPU buffer and open/attach to corresponding >>> perf_event only on CPUs present and online at the moment of perf_buffer >>> creation. Without this logic, perf_buffer creation has no chances of >>> succeeding on such systems, preventing valid and correct BPF applications from >>> starting. >> >> Once CPU goes back online and processes BPF events, any attempt to push into >> perf RB via bpf_perf_event_output() with flag BPF_F_CURRENT_CPU would silently > > bpf_perf_event_output() will return error code in such case, so it's > not exactly undetectable by application. Yeah, true, given there would be no element in the perf map at that slot, the program would receive -ENOENT and we could account for missed events via per CPU map or such. >> get discarded. Should rather perf API be fixed instead of plain skipping as done >> here to at least allow creation of ring buffer for BPF to avoid such case? > > Can you elaborate on what perf API fix you have in mind? Do you mean > for perf to allow attaching ring buffer to offline CPU or something > else? Yes, was wondering about the former, meaning, possibility to attach ring buffer to offline CPU. >>> Andrii Nakryiko (4): >>> libbpf: extract and generalize CPU mask parsing logic >>> selftests/bpf: add CPU mask parsing tests >>> libbpf: don't attach perf_buffer to offline/missing CPUs >>> selftests/bpf: fix perf_buffer test on systems w/ offline CPUs >>> >>> tools/lib/bpf/libbpf.c | 157 ++++++++++++------ >>> tools/lib/bpf/libbpf_internal.h | 2 + >>> .../selftests/bpf/prog_tests/cpu_mask.c | 78 +++++++++ >>> .../selftests/bpf/prog_tests/perf_buffer.c | 29 +++- >>> 4 files changed, 213 insertions(+), 53 deletions(-) >>> create mode 100644 tools/testing/selftests/bpf/prog_tests/cpu_mask.c >>> >>> -- >>> 2.17.1 >>> ^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH bpf-next 0/4] Fix perf_buffer creation on systems with offline CPUs 2019-12-17 13:00 ` Daniel Borkmann @ 2019-12-20 17:46 ` Andrii Nakryiko 0 siblings, 0 replies; 9+ messages in thread From: Andrii Nakryiko @ 2019-12-20 17:46 UTC (permalink / raw) To: Daniel Borkmann Cc: Andrii Nakryiko, bpf, Networking, Alexei Starovoitov, Kernel Team On Tue, Dec 17, 2019 at 5:00 AM Daniel Borkmann <daniel@iogearbox.net> wrote: > > On 12/16/19 6:59 PM, Andrii Nakryiko wrote: > > On Mon, Dec 16, 2019 at 6:44 AM Daniel Borkmann <daniel@iogearbox.net> wrote: > >> On Wed, Dec 11, 2019 at 05:35:20PM -0800, Andrii Nakryiko wrote: > >>> This patch set fixes perf_buffer__new() behavior on systems which have some of > >>> the CPUs offline/missing (due to difference between "possible" and "online" > >>> sets). perf_buffer will create per-CPU buffer and open/attach to corresponding > >>> perf_event only on CPUs present and online at the moment of perf_buffer > >>> creation. Without this logic, perf_buffer creation has no chances of > >>> succeeding on such systems, preventing valid and correct BPF applications from > >>> starting. > >> > >> Once CPU goes back online and processes BPF events, any attempt to push into > >> perf RB via bpf_perf_event_output() with flag BPF_F_CURRENT_CPU would silently > > > > bpf_perf_event_output() will return error code in such case, so it's > > not exactly undetectable by application. > > Yeah, true, given there would be no element in the perf map at that slot, the > program would receive -ENOENT and we could account for missed events via per > CPU map or such. > > >> get discarded. Should rather perf API be fixed instead of plain skipping as done > >> here to at least allow creation of ring buffer for BPF to avoid such case? > > > > Can you elaborate on what perf API fix you have in mind? Do you mean > > for perf to allow attaching ring buffer to offline CPU or something > > else? > > Yes, was wondering about the former, meaning, possibility to attach ring buffer > to offline CPU. This sounds like a more heavy-weight fix, I'll put it on backburner for now and will look at perf code when I get a chance to see if/how it's possible. > > >>> Andrii Nakryiko (4): > >>> libbpf: extract and generalize CPU mask parsing logic > >>> selftests/bpf: add CPU mask parsing tests > >>> libbpf: don't attach perf_buffer to offline/missing CPUs > >>> selftests/bpf: fix perf_buffer test on systems w/ offline CPUs > >>> > >>> tools/lib/bpf/libbpf.c | 157 ++++++++++++------ > >>> tools/lib/bpf/libbpf_internal.h | 2 + > >>> .../selftests/bpf/prog_tests/cpu_mask.c | 78 +++++++++ > >>> .../selftests/bpf/prog_tests/perf_buffer.c | 29 +++- > >>> 4 files changed, 213 insertions(+), 53 deletions(-) > >>> create mode 100644 tools/testing/selftests/bpf/prog_tests/cpu_mask.c > >>> > >>> -- > >>> 2.17.1 > >>> > ^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH bpf-next 0/4] Fix perf_buffer creation on systems with offline CPUs 2019-12-12 1:35 [PATCH bpf-next 0/4] Fix perf_buffer creation on systems with offline CPUs Andrii Nakryiko 2019-12-13 21:04 ` Alexei Starovoitov 2019-12-16 14:44 ` Daniel Borkmann @ 2020-02-09 17:18 ` Naresh Kamboju 2020-02-09 18:32 ` Andrii Nakryiko 2 siblings, 1 reply; 9+ messages in thread From: Naresh Kamboju @ 2020-02-09 17:18 UTC (permalink / raw) To: Andrii Nakryiko, Greg Kroah-Hartman, Sasha Levin Cc: bpf, Netdev, ast, Daniel Borkmann, Andrii Nakryiko, Kernel Team, linux- stable, lkft-triage, Arnaldo Carvalho de Melo, Leo Yan On Thu, 12 Dec 2019 at 07:05, Andrii Nakryiko <andriin@fb.com> wrote: > > This patch set fixes perf_buffer__new() behavior on systems which have some of > the CPUs offline/missing (due to difference between "possible" and "online" > sets). perf_buffer will create per-CPU buffer and open/attach to corresponding > perf_event only on CPUs present and online at the moment of perf_buffer > creation. Without this logic, perf_buffer creation has no chances of > succeeding on such systems, preventing valid and correct BPF applications from > starting. > > Andrii Nakryiko (4): > libbpf: extract and generalize CPU mask parsing logic > selftests/bpf: add CPU mask parsing tests > libbpf: don't attach perf_buffer to offline/missing CPUs perf build failed on stable-rc 5.5 branch. libbpf.c: In function '__perf_buffer__new': libbpf.c:6159:8: error: implicit declaration of function 'parse_cpu_mask_file'; did you mean 'parse_uint_from_file'? [-Werror=implicit-function-declaration] err = parse_cpu_mask_file(online_cpus_file, &online, &n); ^~~~~~~~~~~~~~~~~~~ parse_uint_from_file libbpf.c:6159:8: error: nested extern declaration of 'parse_cpu_mask_file' [-Werror=nested-externs] build log, https://ci.linaro.org/view/lkft/job/openembedded-lkft-linux-stable-rc-5.5/DISTRO=lkft,MACHINE=hikey,label=docker-lkft/11/console -- Linaro LKFT https://lkft.linaro.org ^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH bpf-next 0/4] Fix perf_buffer creation on systems with offline CPUs 2020-02-09 17:18 ` Naresh Kamboju @ 2020-02-09 18:32 ` Andrii Nakryiko 2020-02-09 21:03 ` Greg Kroah-Hartman 0 siblings, 1 reply; 9+ messages in thread From: Andrii Nakryiko @ 2020-02-09 18:32 UTC (permalink / raw) To: Naresh Kamboju Cc: Andrii Nakryiko, Greg Kroah-Hartman, Sasha Levin, bpf, Netdev, Alexei Starovoitov, Daniel Borkmann, Kernel Team, linux- stable, lkft-triage, Arnaldo Carvalho de Melo, Leo Yan On Sun, Feb 9, 2020 at 9:18 AM Naresh Kamboju <naresh.kamboju@linaro.org> wrote: > > On Thu, 12 Dec 2019 at 07:05, Andrii Nakryiko <andriin@fb.com> wrote: > > > > This patch set fixes perf_buffer__new() behavior on systems which have some of > > the CPUs offline/missing (due to difference between "possible" and "online" > > sets). perf_buffer will create per-CPU buffer and open/attach to corresponding > > perf_event only on CPUs present and online at the moment of perf_buffer > > creation. Without this logic, perf_buffer creation has no chances of > > succeeding on such systems, preventing valid and correct BPF applications from > > starting. > > > > Andrii Nakryiko (4): > > libbpf: extract and generalize CPU mask parsing logic > > selftests/bpf: add CPU mask parsing tests > > libbpf: don't attach perf_buffer to offline/missing CPUs > > perf build failed on stable-rc 5.5 branch. > > libbpf.c: In function '__perf_buffer__new': > libbpf.c:6159:8: error: implicit declaration of function > 'parse_cpu_mask_file'; did you mean 'parse_uint_from_file'? > [-Werror=implicit-function-declaration] > err = parse_cpu_mask_file(online_cpus_file, &online, &n); > ^~~~~~~~~~~~~~~~~~~ > parse_uint_from_file > libbpf.c:6159:8: error: nested extern declaration of > 'parse_cpu_mask_file' [-Werror=nested-externs] > > build log, > https://ci.linaro.org/view/lkft/job/openembedded-lkft-linux-stable-rc-5.5/DISTRO=lkft,MACHINE=hikey,label=docker-lkft/11/console > Thanks for reporting! These changes depend on commit 6803ee25f0ea ("libbpf: Extract and generalize CPU mask parsing logic"), which weren't backported to stable. Greg, can you please pull that one as well? Thanks! > -- > Linaro LKFT > https://lkft.linaro.org ^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH bpf-next 0/4] Fix perf_buffer creation on systems with offline CPUs 2020-02-09 18:32 ` Andrii Nakryiko @ 2020-02-09 21:03 ` Greg Kroah-Hartman 0 siblings, 0 replies; 9+ messages in thread From: Greg Kroah-Hartman @ 2020-02-09 21:03 UTC (permalink / raw) To: Andrii Nakryiko Cc: Naresh Kamboju, Andrii Nakryiko, Sasha Levin, bpf, Netdev, Alexei Starovoitov, Daniel Borkmann, Kernel Team, linux- stable, lkft-triage, Arnaldo Carvalho de Melo, Leo Yan On Sun, Feb 09, 2020 at 10:32:43AM -0800, Andrii Nakryiko wrote: > On Sun, Feb 9, 2020 at 9:18 AM Naresh Kamboju <naresh.kamboju@linaro.org> wrote: > > > > On Thu, 12 Dec 2019 at 07:05, Andrii Nakryiko <andriin@fb.com> wrote: > > > > > > This patch set fixes perf_buffer__new() behavior on systems which have some of > > > the CPUs offline/missing (due to difference between "possible" and "online" > > > sets). perf_buffer will create per-CPU buffer and open/attach to corresponding > > > perf_event only on CPUs present and online at the moment of perf_buffer > > > creation. Without this logic, perf_buffer creation has no chances of > > > succeeding on such systems, preventing valid and correct BPF applications from > > > starting. > > > > > > Andrii Nakryiko (4): > > > libbpf: extract and generalize CPU mask parsing logic > > > selftests/bpf: add CPU mask parsing tests > > > libbpf: don't attach perf_buffer to offline/missing CPUs > > > > perf build failed on stable-rc 5.5 branch. > > > > libbpf.c: In function '__perf_buffer__new': > > libbpf.c:6159:8: error: implicit declaration of function > > 'parse_cpu_mask_file'; did you mean 'parse_uint_from_file'? > > [-Werror=implicit-function-declaration] > > err = parse_cpu_mask_file(online_cpus_file, &online, &n); > > ^~~~~~~~~~~~~~~~~~~ > > parse_uint_from_file > > libbpf.c:6159:8: error: nested extern declaration of > > 'parse_cpu_mask_file' [-Werror=nested-externs] > > > > build log, > > https://ci.linaro.org/view/lkft/job/openembedded-lkft-linux-stable-rc-5.5/DISTRO=lkft,MACHINE=hikey,label=docker-lkft/11/console > > > > Thanks for reporting! > > These changes depend on commit 6803ee25f0ea ("libbpf: Extract and > generalize CPU mask parsing logic"), which weren't backported to > stable. Greg, can you please pull that one as well? Thanks! Now applied, thanks! greg k-h ^ permalink raw reply [flat|nested] 9+ messages in thread
end of thread, other threads:[~2020-02-09 21:03 UTC | newest] Thread overview: 9+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2019-12-12 1:35 [PATCH bpf-next 0/4] Fix perf_buffer creation on systems with offline CPUs Andrii Nakryiko 2019-12-13 21:04 ` Alexei Starovoitov 2019-12-16 14:44 ` Daniel Borkmann 2019-12-16 17:59 ` Andrii Nakryiko 2019-12-17 13:00 ` Daniel Borkmann 2019-12-20 17:46 ` Andrii Nakryiko 2020-02-09 17:18 ` Naresh Kamboju 2020-02-09 18:32 ` Andrii Nakryiko 2020-02-09 21:03 ` Greg Kroah-Hartman
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