Impact: enhances lost events counting in mmiotrace The tracing framework, or the ring buffer facility it uses, has a switch to stop recording data. When recording is off, the trace events will be lost. The framework does not count these, so mmiotrace has to count them itself.
Unified · Split
| @@ -9,6 +9,7 @@ · 8 unmodified lines | ||
| 9 | 9 | #include <linux/kernel.h> |
| 10 | 10 | #include <linux/mmiotrace.h> |
| 11 | 11 | #include <linux/pci.h> |
| 12 | +#include <asm/atomic.h> | |
| 12 | 13 | |
| 13 | 14 | #include "trace.h" |
| 14 | 15 | #include "trace_output.h" |
| @@ -20,6 +21,7 @@ struct header_iter { · 5 unmodified lines | ||
| 20 | 21 | static struct trace_array *mmio_trace_array; |
| 21 | 22 | static bool overrun_detected; |
| 22 | 23 | static unsigned long prev_overruns; |
| 24 | +static atomic_t dropped_count; | |
| 23 | 25 | |
| 24 | 26 | static void mmio_reset_data(struct trace_array *tr) |
| 25 | 27 | { |
| @@ -122,11 +124,11 @@ static void mmio_close(struct trace_iterator *iter) · 96 unmodified lines | ||
| 122 | 124 | |
| 123 | 125 | static unsigned long count_overruns(struct trace_iterator *iter) |
| 124 | 126 | { |
| 125 | − unsigned long cnt = 0; | |
| 127 | + unsigned long cnt = atomic_xchg(&dropped_count, 0); | |
| 126 | 128 | unsigned long over = ring_buffer_overruns(iter->tr->buffer); |
| 127 | 129 | |
| 128 | 130 | if (over > prev_overruns) |
| 129 | − cnt = over - prev_overruns; | |
| 131 | + cnt += over - prev_overruns; | |
| 130 | 132 | prev_overruns = over; |
| 131 | 133 | return cnt; |
| 132 | 134 | } |
| @@ -308,8 +310,10 @@ static void __trace_mmiotrace_rw(struct trace_array *tr, · 175 unmodified lines | ||
| 308 | 310 | |
| 309 | 311 | event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry), |
| 310 | 312 | &irq_flags); |
| 311 | − if (!event) | |
| 313 | + if (!event) { | |
| 314 | + atomic_inc(&dropped_count); | |
| 312 | 315 | return; |
| 316 | + } | |
| 313 | 317 | entry = ring_buffer_event_data(event); |
| 314 | 318 | tracing_generic_entry_update(&entry->ent, 0, preempt_count()); |
| 315 | 319 | entry->ent.type = TRACE_MMIO_RW; |
| @@ -336,8 +340,10 @@ static void __trace_mmiotrace_map(struct trace_array *tr, · 20 unmodified lines | ||
| 336 | 340 | |
| 337 | 341 | event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry), |
| 338 | 342 | &irq_flags); |
| 339 | − if (!event) | |
| 343 | + if (!event) { | |
| 344 | + atomic_inc(&dropped_count); | |
| 340 | 345 | return; |
| 346 | + } | |
| 341 | 347 | entry = ring_buffer_event_data(event); |
| 342 | 348 | tracing_generic_entry_update(&entry->ent, 0, preempt_count()); |
| 343 | 349 | entry->ent.type = TRACE_MMIO_MAP; |