[RFC PATCH 13/17] perf: Re-inject shmem buffers after exec

From	Alexander Shishkin <alexander.shishkin@linux.intel.com>
Newsgroups	linux.kernel
Subject	[RFC PATCH 13/17] perf: Re-inject shmem buffers after exec
Date	2017-09-05 16:00 +0200
Message-ID	<ummyu-3m5-9@gated-at.bofh.it> (permalink)
References	<ummf8-3dY-9@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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A exec will unmap everything, but we want our shmem buffers to persist.
This tells the page-pinning task work to mmap event's ring buffer after
the task exec'ed.

Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
---
 kernel/events/core.c | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/kernel/events/core.c b/kernel/events/core.c
index e00f1f6aaf..f0b77b33b4 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -6482,6 +6482,29 @@ static void perf_event_addr_filters_exec(struct perf_event *event, void *data)
 		perf_event_stop(event, 1);
 }
 
+static void perf_shmem_ctx_exec(struct perf_event_context *ctx)
+{
+	struct perf_event *event;
+	unsigned long flags;
+
+	raw_spin_lock_irqsave(&ctx->lock, flags);
+
+	list_for_each_entry(event, &ctx->event_list, event_entry) {
+		if (event->attach_state & PERF_ATTACH_SHMEM) {
+			struct ring_buffer *rb;
+
+			/* called inside rcu read section */
+			rb = rcu_dereference(event->rb);
+			if (!rb)
+				continue;
+
+			rb->shmem_file_addr = 0;
+		}
+	}
+
+	raw_spin_unlock_irqrestore(&ctx->lock, flags);
+}
+
 void perf_event_exec(void)
 {
 	struct perf_event_context *ctx;
@@ -6497,6 +6520,7 @@ void perf_event_exec(void)
 
 		perf_iterate_ctx(ctx, perf_event_addr_filters_exec, NULL,
 				   true);
+		perf_shmem_ctx_exec(ctx);
 	}
 	rcu_read_unlock();
 }
-- 
2.14.1

Thread

[RFC PATCH 00/17] perf: Detached events Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2017-09-05 15:40 +0200
  [RFC PATCH 04/17] tracefs: Add ->unlink callback to tracefs_dir_ops Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2017-09-05 15:40 +0200
  [RFC PATCH 05/17] perf: Introduce detached events Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2017-09-05 15:40 +0200
  [RFC PATCH 01/17] perf: Allow mmapping only user page Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2017-09-05 15:40 +0200
    Re: [RFC PATCH 01/17] perf: Allow mmapping only user page Borislav Petkov <bp@alien8.de> - 2017-09-06 18:30 +0200
  [RFC PATCH 03/17] tracefs: De-globalize instances' callbacks Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2017-09-05 15:40 +0200
  [RFC PATCH 02/17] perf: Factor out mlock accounting Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2017-09-05 15:40 +0200
  [RFC PATCH 08/17] perf: Allow inheritance for detached events Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2017-09-05 15:50 +0200
  [RFC PATCH 10/17] perf: Implement pinning and scheduling for SHMEM events Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2017-09-05 15:50 +0200
  [RFC PATCH 07/17] perf: Add pmu_info to user page Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2017-09-05 15:50 +0200
  [RFC PATCH 06/17] perf: Add buffers to the detached events Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2017-09-05 15:50 +0200
  [RFC PATCH 09/17] perf: Use shmemfs pages for userspace-only per-thread detached events Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2017-09-05 15:50 +0200
  [RFC PATCH 11/17] perf: Implement mlock accounting for shmem ring buffers Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2017-09-05 15:50 +0200
  [RFC PATCH 12/17] perf: Track pinned events per user Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2017-09-05 16:00 +0200
  [RFC PATCH 13/17] perf: Re-inject shmem buffers after exec Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2017-09-05 16:00 +0200
  [RFC PATCH 14/17] perf: Add ioctl(REATTACH) for detached events Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2017-09-05 16:00 +0200
  [RFC PATCH 16/17] perf/x86/intel/pt: Add PMU info Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2017-09-05 16:10 +0200
  [RFC PATCH 17/17] perf/x86/intel/bts: Add PMU info Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2017-09-05 16:10 +0200
  [RFC PATCH 15/17] perf: Allow controlled non-root access to detached events Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2017-09-05 16:10 +0200
  Re: [RFC PATCH 00/17] perf: Detached events Borislav Petkov <bp@alien8.de> - 2017-09-06 18:30 +0200

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