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Diffstat (limited to 'Documentation/tracepoints.txt')
| -rw-r--r-- | Documentation/tracepoints.txt | 10 |
1 files changed, 6 insertions, 4 deletions
diff --git a/Documentation/tracepoints.txt b/Documentation/tracepoints.txt index e8ad47b437f3..93cd90e89cc1 100644 --- a/Documentation/tracepoints.txt +++ b/Documentation/tracepoints.txt | |||
| @@ -70,10 +70,12 @@ Where : | |||
| 70 | Connecting a function (probe) to a tracepoint is done by providing a probe | 70 | Connecting a function (probe) to a tracepoint is done by providing a probe |
| 71 | (function to call) for the specific tracepoint through | 71 | (function to call) for the specific tracepoint through |
| 72 | register_trace_subsys_eventname(). Removing a probe is done through | 72 | register_trace_subsys_eventname(). Removing a probe is done through |
| 73 | unregister_trace_subsys_eventname(); it will remove the probe sure there is no | 73 | unregister_trace_subsys_eventname(); it will remove the probe. |
| 74 | caller left using the probe when it returns. Probe removal is preempt-safe | 74 | marker_synchronize_unregister() must be called before the end of the module exit |
| 75 | because preemption is disabled around the probe call. See the "Probe example" | 75 | function to make sure there is no caller left using the probe. This, and the |
| 76 | section below for a sample probe module. | 76 | fact that preemption is disabled around the probe call, make sure that probe |
| 77 | removal and module unload are safe. See the "Probe example" section below for a | ||
| 78 | sample probe module. | ||
| 77 | 79 | ||
| 78 | The tracepoint mechanism supports inserting multiple instances of the same | 80 | The tracepoint mechanism supports inserting multiple instances of the same |
| 79 | tracepoint, but a single definition must be made of a given tracepoint name over | 81 | tracepoint, but a single definition must be made of a given tracepoint name over |