diff options
| author |   Mathieu Poirier <mathieu.poirier@linaro.org> | 2016-05-03 11:33:53 -0600 |
|---|---|---|
| committer |   Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2016-05-03 14:59:30 -0700 |
| commit | f74debbea0885ebb65fb3fa4e598323f40b03f5f (patch) | |
| tree | e103d1b63fa7d710354ca2ec80e7ec38cf47fe60 /drivers/hwtracing/coresight/coresight-tmc-etf.c | |
| parent | coresight: tmc: allocating memory when needed (diff) | |
| download | linux-dev-f74debbea0885ebb65fb3fa4e598323f40b03f5f.tar.xz linux-dev-f74debbea0885ebb65fb3fa4e598323f40b03f5f.zip | |
coresight: tmc: getting rid of multiple read access
Allowing multiple readers to access the trace data simultaniously
via sysFS provides no shortage of opportunity for race condition,
mandates two variable to be maintained (drvdata::read_count and
drvdata::reading), makes the code complex and provide little
advantages, if any.
This patch streamlines the read process by restricting trace data
access to a single user. That way drvdata::read_count can
be eliminated and race conditions (along with faulty error handling)
in function tmc_open() and tmc_release() eliminated.
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/hwtracing/coresight/coresight-tmc-etf.c')
| -rw-r--r-- | drivers/hwtracing/coresight/coresight-tmc-etf.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/drivers/hwtracing/coresight/coresight-tmc-etf.c b/drivers/hwtracing/coresight/coresight-tmc-etf.c index 6eb1665cfc9c..60edf4d1968f 100644 --- a/drivers/hwtracing/coresight/coresight-tmc-etf.c +++ b/drivers/hwtracing/coresight/coresight-tmc-etf.c @@ -260,6 +260,11 @@ int tmc_read_prepare_etb(struct tmc_drvdata *drvdata) spin_lock_irqsave(&drvdata->spinlock, flags); + if (drvdata->reading) { + ret = -EBUSY; + goto out; + } + /* There is no point in reading a TMC in HW FIFO mode */ mode = readl_relaxed(drvdata->base + TMC_MODE); if (mode != TMC_MODE_CIRCULAR_BUFFER) { |