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[PATCH 2/4] ftrace/instances: Clear function triggers when removing instances

Started by"Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>
First post2017-05-13 21:40 +0200
Last post2017-05-16 20:40 +0200
Articles 8 — 3 participants

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  [PATCH 2/4] ftrace/instances: Clear function triggers when removing instances "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com> - 2017-05-13 21:40 +0200
    Re: [PATCH 2/4] ftrace/instances: Clear function triggers when  removing instances Steven Rostedt <rostedt@goodmis.org> - 2017-05-15 17:30 +0200
      Re: [PATCH 2/4] ftrace/instances: Clear function triggers when  removing instances Steven Rostedt <rostedt@goodmis.org> - 2017-05-15 18:20 +0200
        Re: [PATCH 2/4] ftrace/instances: Clear function triggers when  removing instances Masami Hiramatsu <mhiramat@kernel.org> - 2017-05-16 18:20 +0200
    Re: [PATCH 2/4] ftrace/instances: Clear function triggers when  removing instances Steven Rostedt <rostedt@goodmis.org> - 2017-05-16 04:30 +0200
      Re: [PATCH 2/4] ftrace/instances: Clear function triggers when  removing instances "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com> - 2017-05-16 16:10 +0200
        Re: [PATCH 2/4] ftrace/instances: Clear function triggers when  removing instances "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com> - 2017-05-16 19:50 +0200
          Re: [PATCH 2/4] ftrace/instances: Clear function triggers when  removing instances Steven Rostedt <rostedt@goodmis.org> - 2017-05-16 20:40 +0200

#1640986 — [PATCH 2/4] ftrace/instances: Clear function triggers when removing instances

From"Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>
Date2017-05-13 21:40 +0200
Subject[PATCH 2/4] ftrace/instances: Clear function triggers when removing instances
Message-ID<tGL3r-7WF-15@gated-at.bofh.it>
If instance directories are deleted while there are registered function
triggers:

  # cd /sys/kernel/debug/tracing/instances
  # mkdir test
  # echo "schedule:enable_event:sched:sched_switch" > test/set_ftrace_filter
  # rmdir test
  Unable to handle kernel paging request for data at address 0x00000008
  Unable to handle kernel paging request for data at address 0x00000008
  Faulting instruction address: 0xc0000000021edde8
  Oops: Kernel access of bad area, sig: 11 [#1]
  SMP NR_CPUS=2048
  NUMA
  pSeries
  Modules linked in: iptable_mangle ipt_MASQUERADE nf_nat_masquerade_ipv4 iptable_nat nf_nat_ipv4 nf_nat nf_conntrack_ipv4 nf_defrag_ipv4 xt_conntrack nf_conntrack ipt_REJECT nf_reject_ipv4 xt_tcpudp tun bridge stp llc kvm iptable_filter fuse binfmt_misc pseries_rng rng_core vmx_crypto ib_iser rdma_cm iw_cm ib_cm ib_core libiscsi scsi_transport_iscsi ip_tables x_tables autofs4 btrfs raid10 raid456 async_raid6_recov async_memcpy async_pq async_xor async_tx xor raid6_pq libcrc32c multipath virtio_net virtio_blk virtio_pci crc32c_vpmsum virtio_ring virtio
  CPU: 8 PID: 8694 Comm: rmdir Not tainted 4.11.0-nnr+ #113
  task: c0000000bab52800 task.stack: c0000000baba0000
  NIP: c0000000021edde8 LR: c0000000021f0590 CTR: c000000002119620
  REGS: c0000000baba3870 TRAP: 0300   Not tainted  (4.11.0-nnr+)
  MSR: 8000000000009033 <SF,EE,ME,IR,DR,RI,LE>
    CR: 22002422  XER: 20000000
  CFAR: 00007fffabb725a8 DAR: 0000000000000008 DSISR: 40000000 SOFTE: 0
  GPR00: c00000000220f750 c0000000baba3af0 c000000003157e00 0000000000000000
  GPR04: 0000000000000040 00000000000000eb 0000000000000040 0000000000000000
  GPR08: 0000000000000000 0000000000000113 0000000000000000 c00000000305db98
  GPR12: c000000002119620 c00000000fd42c00 0000000000000000 0000000000000000
  GPR16: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
  GPR20: 0000000000000000 0000000000000000 c0000000bab52e90 0000000000000000
  GPR24: 0000000000000000 00000000000000eb 0000000000000040 c0000000baba3bb0
  GPR28: c00000009cb06eb0 c0000000bab52800 c00000009cb06eb0 c0000000baba3bb0
  NIP [c0000000021edde8] ring_buffer_lock_reserve+0x8/0x4e0
  LR [c0000000021f0590] trace_event_buffer_lock_reserve+0xe0/0x1a0
  Call Trace:
  [c0000000baba3af0] [c0000000021f96c8] trace_event_buffer_commit+0x1b8/0x280 (unreliable)
  [c0000000baba3b60] [c00000000220f750] trace_event_buffer_reserve+0x80/0xd0
  [c0000000baba3b90] [c0000000021196b8] trace_event_raw_event_sched_switch+0x98/0x180
  [c0000000baba3c10] [c0000000029d9980] __schedule+0x6e0/0xab0
  [c0000000baba3ce0] [c000000002122230] do_task_dead+0x70/0xc0
  [c0000000baba3d10] [c0000000020ea9c8] do_exit+0x828/0xd00
  [c0000000baba3dd0] [c0000000020eaf70] do_group_exit+0x60/0x100
  [c0000000baba3e10] [c0000000020eb034] SyS_exit_group+0x24/0x30
  [c0000000baba3e30] [c00000000200bcec] system_call+0x38/0x54
  Instruction dump:
  60000000 60420000 7d244b78 7f63db78 4bffaa09 393efff8 793e0020 39200000
  4bfffecc 60420000 3c4c00f7 3842a020 <81230008> 2f890000 409e02f0 a14d0008
  ---[ end trace b917b8985d0e650b ]---
  Unable to handle kernel paging request for data at address 0x00000008
  Faulting instruction address: 0xc0000000021edde8
  Unable to handle kernel paging request for data at address 0x00000008
  Faulting instruction address: 0xc0000000021edde8
  Faulting instruction address: 0xc0000000021edde8

To address this, let's clear all registered function probes before
deleting the ftrace instance.

Reported-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
---
 kernel/trace/ftrace.c | 8 ++++++++
 kernel/trace/trace.c  | 1 +
 kernel/trace/trace.h  | 1 +
 3 files changed, 10 insertions(+)

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 28dc824ad072..1b96d927a082 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -4256,6 +4256,14 @@ unregister_ftrace_function_probe_func(char *glob, struct trace_array *tr,
 	return ret;
 }
 
+void clear_ftrace_function_probes(struct trace_array *tr)
+{
+	struct ftrace_func_probe *probe, *n;
+
+	list_for_each_entry_safe(probe, n, &tr->func_probes, list)
+		unregister_ftrace_function_probe_func(NULL, tr, probe->probe_ops);
+}
+
 static LIST_HEAD(ftrace_commands);
 static DEFINE_MUTEX(ftrace_cmd_mutex);
 
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index c4536c449021..3f2aed4ad1ed 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -7550,6 +7550,7 @@ static int instance_rmdir(const char *name)
 	}
 
 	tracing_set_nop(tr);
+	clear_ftrace_function_probes(tr);
 	event_trace_del_tracer(tr);
 	ftrace_clear_pids(tr);
 	ftrace_destroy_function_files(tr);
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 291a1bca5748..98e0845f7235 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -980,6 +980,7 @@ register_ftrace_function_probe(char *glob, struct trace_array *tr,
 extern int
 unregister_ftrace_function_probe_func(char *glob, struct trace_array *tr,
 				      struct ftrace_probe_ops *ops);
+extern void clear_ftrace_function_probes(struct trace_array *tr);
 
 int register_ftrace_command(struct ftrace_func_command *cmd);
 int unregister_ftrace_command(struct ftrace_func_command *cmd);
-- 
2.12.2

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#1641809 — Re: [PATCH 2/4] ftrace/instances: Clear function triggers when removing instances

FromSteven Rostedt <rostedt@goodmis.org>
Date2017-05-15 17:30 +0200
SubjectRe: [PATCH 2/4] ftrace/instances: Clear function triggers when removing instances
Message-ID<tHq6C-1u3-13@gated-at.bofh.it>
In reply to#1640986
On Sun, 14 May 2017 01:01:02 +0530
"Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com> wrote:

> If instance directories are deleted while there are registered function
> triggers:
> 
>   # cd /sys/kernel/debug/tracing/instances
>   # mkdir test
>   # echo "schedule:enable_event:sched:sched_switch" > test/set_ftrace_filter
>   # rmdir test
>   Unable to handle kernel paging request for data at address 0x00000008
>   Unable to handle kernel paging request for data at address 0x00000008
>   Faulting instruction address: 0xc0000000021edde8
>   Oops: Kernel access of bad area, sig: 11 [#1]
>   SMP NR_CPUS=2048
>   NUMA
>   pSeries

Looks like this patch needs to be marked for stable, and go in right
away. I may also do the same for the ftracetest bashism patch with
Masami's approval. I may also slip in the ftracetest for the bug that
this patch fixes.

The first patch can go into the queue for 4.13.

-- Steve

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#1641867 — Re: [PATCH 2/4] ftrace/instances: Clear function triggers when removing instances

FromSteven Rostedt <rostedt@goodmis.org>
Date2017-05-15 18:20 +0200
SubjectRe: [PATCH 2/4] ftrace/instances: Clear function triggers when removing instances
Message-ID<tHqT0-1Zv-5@gated-at.bofh.it>
In reply to#1641809
On Mon, 15 May 2017 11:21:15 -0400
Steven Rostedt <rostedt@goodmis.org> wrote:

> On Sun, 14 May 2017 01:01:02 +0530
> "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com> wrote:
> 
> > If instance directories are deleted while there are registered function
> > triggers:
> > 
> >   # cd /sys/kernel/debug/tracing/instances
> >   # mkdir test
> >   # echo "schedule:enable_event:sched:sched_switch" > test/set_ftrace_filter
> >   # rmdir test
> >   Unable to handle kernel paging request for data at address 0x00000008
> >   Unable to handle kernel paging request for data at address 0x00000008
> >   Faulting instruction address: 0xc0000000021edde8
> >   Oops: Kernel access of bad area, sig: 11 [#1]
> >   SMP NR_CPUS=2048
> >   NUMA
> >   pSeries  
> 
> Looks like this patch needs to be marked for stable, and go in right
> away. I may also do the same for the ftracetest bashism patch with
> Masami's approval. I may also slip in the ftracetest for the bug that
> this patch fixes.

As this patch fixes a bug that was introduced with the 4.12 merge
window. Thus, it's not stable worthy (stable isn't affected). Although,
I'll wait on Masami to see if that should go to stable.

-- Steve

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#1642657 — Re: [PATCH 2/4] ftrace/instances: Clear function triggers when removing instances

FromMasami Hiramatsu <mhiramat@kernel.org>
Date2017-05-16 18:20 +0200
SubjectRe: [PATCH 2/4] ftrace/instances: Clear function triggers when removing instances
Message-ID<tHNmz-7PP-41@gated-at.bofh.it>
In reply to#1641867
On Mon, 15 May 2017 12:11:03 -0400
Steven Rostedt <rostedt@goodmis.org> wrote:

> On Mon, 15 May 2017 11:21:15 -0400
> Steven Rostedt <rostedt@goodmis.org> wrote:
> 
> > On Sun, 14 May 2017 01:01:02 +0530
> > "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com> wrote:
> > 
> > > If instance directories are deleted while there are registered function
> > > triggers:
> > > 
> > >   # cd /sys/kernel/debug/tracing/instances
> > >   # mkdir test
> > >   # echo "schedule:enable_event:sched:sched_switch" > test/set_ftrace_filter
> > >   # rmdir test
> > >   Unable to handle kernel paging request for data at address 0x00000008
> > >   Unable to handle kernel paging request for data at address 0x00000008
> > >   Faulting instruction address: 0xc0000000021edde8
> > >   Oops: Kernel access of bad area, sig: 11 [#1]
> > >   SMP NR_CPUS=2048
> > >   NUMA
> > >   pSeries  
> > 
> > Looks like this patch needs to be marked for stable, and go in right
> > away. I may also do the same for the ftracetest bashism patch with
> > Masami's approval. I may also slip in the ftracetest for the bug that
> > this patch fixes.
> 
> As this patch fixes a bug that was introduced with the 4.12 merge
> window. Thus, it's not stable worthy (stable isn't affected). Although,
> I'll wait on Masami to see if that should go to stable.

Hm, for the bashism fix, that is not a show-stopper... and also,
newer ftracetest should work on older kernel. So I don't think
it needs to go stable.

Thank you, 

> 
> -- Steve
> 


-- 
Masami Hiramatsu <mhiramat@kernel.org>

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#1642187 — Re: [PATCH 2/4] ftrace/instances: Clear function triggers when removing instances

FromSteven Rostedt <rostedt@goodmis.org>
Date2017-05-16 04:30 +0200
SubjectRe: [PATCH 2/4] ftrace/instances: Clear function triggers when removing instances
Message-ID<tHApk-842-5@gated-at.bofh.it>
In reply to#1640986
On Sun, 14 May 2017 01:01:02 +0530
"Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com> wrote:

> If instance directories are deleted while there are registered function
> triggers:
> 
>   # cd /sys/kernel/debug/tracing/instances
>   # mkdir test
>   # echo "schedule:enable_event:sched:sched_switch" > test/set_ftrace_filter
>   # rmdir test
>   Unable to handle kernel paging request for data at address 0x00000008
>   Unable to handle kernel paging request for data at address 0x00000008
>   Faulting instruction address: 0xc0000000021edde8
>   Oops: Kernel access of bad area, sig: 11 [#1]
>   SMP NR_CPUS=2048
>   NUMA
>   pSeries
>   Modules linked in: iptable_mangle ipt_MASQUERADE nf_nat_masquerade_ipv4 iptable_nat nf_nat_ipv4 nf_nat nf_conntrack_ipv4 nf_defrag_ipv4 xt_conntrack nf_conntrack ipt_REJECT nf_reject_ipv4 xt_tcpudp tun bridge stp llc kvm iptable_filter fuse binfmt_misc pseries_rng rng_core vmx_crypto ib_iser rdma_cm iw_cm ib_cm ib_core libiscsi scsi_transport_iscsi ip_tables x_tables autofs4 btrfs raid10 raid456 async_raid6_recov async_memcpy async_pq async_xor async_tx xor raid6_pq libcrc32c multipath virtio_net virtio_blk virtio_pci crc32c_vpmsum virtio_ring virtio
>   CPU: 8 PID: 8694 Comm: rmdir Not tainted 4.11.0-nnr+ #113
>   task: c0000000bab52800 task.stack: c0000000baba0000
>   NIP: c0000000021edde8 LR: c0000000021f0590 CTR: c000000002119620
>   REGS: c0000000baba3870 TRAP: 0300   Not tainted  (4.11.0-nnr+)
>   MSR: 8000000000009033 <SF,EE,ME,IR,DR,RI,LE>
>     CR: 22002422  XER: 20000000
>   CFAR: 00007fffabb725a8 DAR: 0000000000000008 DSISR: 40000000 SOFTE: 0
>   GPR00: c00000000220f750 c0000000baba3af0 c000000003157e00 0000000000000000
>   GPR04: 0000000000000040 00000000000000eb 0000000000000040 0000000000000000
>   GPR08: 0000000000000000 0000000000000113 0000000000000000 c00000000305db98
>   GPR12: c000000002119620 c00000000fd42c00 0000000000000000 0000000000000000
>   GPR16: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
>   GPR20: 0000000000000000 0000000000000000 c0000000bab52e90 0000000000000000
>   GPR24: 0000000000000000 00000000000000eb 0000000000000040 c0000000baba3bb0
>   GPR28: c00000009cb06eb0 c0000000bab52800 c00000009cb06eb0 c0000000baba3bb0
>   NIP [c0000000021edde8] ring_buffer_lock_reserve+0x8/0x4e0
>   LR [c0000000021f0590] trace_event_buffer_lock_reserve+0xe0/0x1a0
>   Call Trace:
>   [c0000000baba3af0] [c0000000021f96c8] trace_event_buffer_commit+0x1b8/0x280 (unreliable)
>   [c0000000baba3b60] [c00000000220f750] trace_event_buffer_reserve+0x80/0xd0
>   [c0000000baba3b90] [c0000000021196b8] trace_event_raw_event_sched_switch+0x98/0x180
>   [c0000000baba3c10] [c0000000029d9980] __schedule+0x6e0/0xab0
>   [c0000000baba3ce0] [c000000002122230] do_task_dead+0x70/0xc0
>   [c0000000baba3d10] [c0000000020ea9c8] do_exit+0x828/0xd00
>   [c0000000baba3dd0] [c0000000020eaf70] do_group_exit+0x60/0x100
>   [c0000000baba3e10] [c0000000020eb034] SyS_exit_group+0x24/0x30
>   [c0000000baba3e30] [c00000000200bcec] system_call+0x38/0x54
>   Instruction dump:
>   60000000 60420000 7d244b78 7f63db78 4bffaa09 393efff8 793e0020 39200000
>   4bfffecc 60420000 3c4c00f7 3842a020 <81230008> 2f890000 409e02f0 a14d0008
>   ---[ end trace b917b8985d0e650b ]---
>   Unable to handle kernel paging request for data at address 0x00000008
>   Faulting instruction address: 0xc0000000021edde8
>   Unable to handle kernel paging request for data at address 0x00000008
>   Faulting instruction address: 0xc0000000021edde8
>   Faulting instruction address: 0xc0000000021edde8
> 
> To address this, let's clear all registered function probes before
> deleting the ftrace instance.
> 
> Reported-by: Michael Ellerman <mpe@ellerman.id.au>
> Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
> ---
>  kernel/trace/ftrace.c | 8 ++++++++
>  kernel/trace/trace.c  | 1 +
>  kernel/trace/trace.h  | 1 +
>  3 files changed, 10 insertions(+)
> 
> diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
> index 28dc824ad072..1b96d927a082 100644
> --- a/kernel/trace/ftrace.c
> +++ b/kernel/trace/ftrace.c
> @@ -4256,6 +4256,14 @@ unregister_ftrace_function_probe_func(char *glob, struct trace_array *tr,
>  	return ret;
>  }
>  
> +void clear_ftrace_function_probes(struct trace_array *tr)
> +{
> +	struct ftrace_func_probe *probe, *n;
> +
> +	list_for_each_entry_safe(probe, n, &tr->func_probes, list)
> +		unregister_ftrace_function_probe_func(NULL, tr, probe->probe_ops);
> +}
> +
>  static LIST_HEAD(ftrace_commands);
>  static DEFINE_MUTEX(ftrace_cmd_mutex);
>  
> diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
> index c4536c449021..3f2aed4ad1ed 100644
> --- a/kernel/trace/trace.c
> +++ b/kernel/trace/trace.c
> @@ -7550,6 +7550,7 @@ static int instance_rmdir(const char *name)
>  	}
>  
>  	tracing_set_nop(tr);
> +	clear_ftrace_function_probes(tr);
>  	event_trace_del_tracer(tr);
>  	ftrace_clear_pids(tr);
>  	ftrace_destroy_function_files(tr);
> diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
> index 291a1bca5748..98e0845f7235 100644
> --- a/kernel/trace/trace.h
> +++ b/kernel/trace/trace.h
> @@ -980,6 +980,7 @@ register_ftrace_function_probe(char *glob, struct trace_array *tr,
>  extern int
>  unregister_ftrace_function_probe_func(char *glob, struct trace_array *tr,
>  				      struct ftrace_probe_ops *ops);
> +extern void clear_ftrace_function_probes(struct trace_array *tr);

This needs to have a stub function when CONFIG_DYNAMIC_FTRACE is not
defined. Otherwise we have:

kernel/trace/trace.c:7553:2: error: implicit declaration of function 'clear_ftrace_function_probes' [-Werror=implicit-function-declaration]
  clear_ftrace_function_probes(tr);
  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~

-- Steve

>  
>  int register_ftrace_command(struct ftrace_func_command *cmd);
>  int unregister_ftrace_command(struct ftrace_func_command *cmd);

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#1642572 — Re: [PATCH 2/4] ftrace/instances: Clear function triggers when removing instances

From"Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>
Date2017-05-16 16:10 +0200
SubjectRe: [PATCH 2/4] ftrace/instances: Clear function triggers when removing instances
Message-ID<tHLkK-6BF-3@gated-at.bofh.it>
In reply to#1642187
On 2017/05/15 10:20PM, Steven Rostedt wrote:
> On Sun, 14 May 2017 01:01:02 +0530
> "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com> wrote:
> 

[snip]

> > diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
> > index c4536c449021..3f2aed4ad1ed 100644
> > --- a/kernel/trace/trace.c
> > +++ b/kernel/trace/trace.c
> > @@ -7550,6 +7550,7 @@ static int instance_rmdir(const char *name)
> >  	}
> >  
> >  	tracing_set_nop(tr);
> > +	clear_ftrace_function_probes(tr);
> >  	event_trace_del_tracer(tr);
> >  	ftrace_clear_pids(tr);
> >  	ftrace_destroy_function_files(tr);
> > diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
> > index 291a1bca5748..98e0845f7235 100644
> > --- a/kernel/trace/trace.h
> > +++ b/kernel/trace/trace.h
> > @@ -980,6 +980,7 @@ register_ftrace_function_probe(char *glob, struct trace_array *tr,
> >  extern int
> >  unregister_ftrace_function_probe_func(char *glob, struct trace_array *tr,
> >  				      struct ftrace_probe_ops *ops);
> > +extern void clear_ftrace_function_probes(struct trace_array *tr);
> 
> This needs to have a stub function when CONFIG_DYNAMIC_FTRACE is not
> defined. Otherwise we have:
> 
> kernel/trace/trace.c:7553:2: error: implicit declaration of function 'clear_ftrace_function_probes' [-Werror=implicit-function-declaration]
>   clear_ftrace_function_probes(tr);
>   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~

Ah, ok. I'll respin once Masami comments on the other patches.

Thanks,
Naveen

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#1642697 — Re: [PATCH 2/4] ftrace/instances: Clear function triggers when removing instances

From"Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>
Date2017-05-16 19:50 +0200
SubjectRe: [PATCH 2/4] ftrace/instances: Clear function triggers when removing instances
Message-ID<tHOLE-9u-17@gated-at.bofh.it>
In reply to#1642572
On 2017/05/16 07:31PM, Naveen N. Rao wrote:
> On 2017/05/15 10:20PM, Steven Rostedt wrote:
> > On Sun, 14 May 2017 01:01:02 +0530
> > "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com> wrote:
> > 
> 
> [snip]
> 
> > > diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
> > > index c4536c449021..3f2aed4ad1ed 100644
> > > --- a/kernel/trace/trace.c
> > > +++ b/kernel/trace/trace.c
> > > @@ -7550,6 +7550,7 @@ static int instance_rmdir(const char *name)
> > >  	}
> > >  
> > >  	tracing_set_nop(tr);
> > > +	clear_ftrace_function_probes(tr);
> > >  	event_trace_del_tracer(tr);
> > >  	ftrace_clear_pids(tr);
> > >  	ftrace_destroy_function_files(tr);
> > > diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
> > > index 291a1bca5748..98e0845f7235 100644
> > > --- a/kernel/trace/trace.h
> > > +++ b/kernel/trace/trace.h
> > > @@ -980,6 +980,7 @@ register_ftrace_function_probe(char *glob, struct trace_array *tr,
> > >  extern int
> > >  unregister_ftrace_function_probe_func(char *glob, struct trace_array *tr,
> > >  				      struct ftrace_probe_ops *ops);
> > > +extern void clear_ftrace_function_probes(struct trace_array *tr);
> > 
> > This needs to have a stub function when CONFIG_DYNAMIC_FTRACE is not
> > defined. Otherwise we have:
> > 
> > kernel/trace/trace.c:7553:2: error: implicit declaration of function 'clear_ftrace_function_probes' [-Werror=implicit-function-declaration]
> >   clear_ftrace_function_probes(tr);
> >   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~

The prototype in trace.h is actually guarded by:
#if defined(CONFIG_FUNCTION_TRACER) && defined(CONFIG_DYNAMIC_FTRACE)

So, I will guard the call to clear_ftrace_function_probes() in trace.c 
with the same.

- Naveen

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#1642733 — Re: [PATCH 2/4] ftrace/instances: Clear function triggers when removing instances

FromSteven Rostedt <rostedt@goodmis.org>
Date2017-05-16 20:40 +0200
SubjectRe: [PATCH 2/4] ftrace/instances: Clear function triggers when removing instances
Message-ID<tHPy1-Fy-7@gated-at.bofh.it>
In reply to#1642697
On Tue, 16 May 2017 23:14:23 +0530
"Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com> wrote:

> On 2017/05/16 07:31PM, Naveen N. Rao wrote:
> > On 2017/05/15 10:20PM, Steven Rostedt wrote:  
> > > On Sun, 14 May 2017 01:01:02 +0530
> > > "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com> wrote:
> > >   
> > 
> > [snip]
> >   
> > > > diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
> > > > index c4536c449021..3f2aed4ad1ed 100644
> > > > --- a/kernel/trace/trace.c
> > > > +++ b/kernel/trace/trace.c
> > > > @@ -7550,6 +7550,7 @@ static int instance_rmdir(const char *name)
> > > >  	}
> > > >  
> > > >  	tracing_set_nop(tr);
> > > > +	clear_ftrace_function_probes(tr);
> > > >  	event_trace_del_tracer(tr);
> > > >  	ftrace_clear_pids(tr);
> > > >  	ftrace_destroy_function_files(tr);
> > > > diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
> > > > index 291a1bca5748..98e0845f7235 100644
> > > > --- a/kernel/trace/trace.h
> > > > +++ b/kernel/trace/trace.h
> > > > @@ -980,6 +980,7 @@ register_ftrace_function_probe(char *glob, struct trace_array *tr,
> > > >  extern int
> > > >  unregister_ftrace_function_probe_func(char *glob, struct trace_array *tr,
> > > >  				      struct ftrace_probe_ops *ops);
> > > > +extern void clear_ftrace_function_probes(struct trace_array *tr);  
> > > 
> > > This needs to have a stub function when CONFIG_DYNAMIC_FTRACE is not
> > > defined. Otherwise we have:
> > > 
> > > kernel/trace/trace.c:7553:2: error: implicit declaration of function 'clear_ftrace_function_probes' [-Werror=implicit-function-declaration]
> > >   clear_ftrace_function_probes(tr);
> > >   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~  
> 
> The prototype in trace.h is actually guarded by:
> #if defined(CONFIG_FUNCTION_TRACER) && defined(CONFIG_DYNAMIC_FTRACE)
> 
> So, I will guard the call to clear_ftrace_function_probes() in trace.c 
> with the same.
> 

No, the proper thing to do is to make a stub function in the else part
of the #if that the prototype was declared in.

static inline void clear_ftrace_function_probes(struct trace_array *tr)
{
}

Please, lets limit the #ifdef ugliness from the code.

-- Steve

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