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coresight: tmc-etr: Fix deadlock issue while reading from ETR

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If ETR is being read repeatedly, at the same time, trying to reset
source link again and again, sometimes deadlock problems occur.
Beacause reset_source_sink_store holds coresight_mutex and waits
for mem_lock, meanwhile, tmc_read_prepare_etr holds mem_lock and
waits for coresight_mutex.

Change-Id: I8c70575b8a70d820748492313d6232923478ede3
Signed-off-by: Tao,Zhang <taozha@codeaurora.org>
This commit is contained in:
Tao,Zhang 2020-05-29 16:48:28 +08:00
commit 7c7dfa62ff
1 changed files with 9 additions and 5 deletions
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14
drivers/hwtracing/coresight/coresight-tmc-etr.c
View file

@ -2164,14 +2164,18 @@ int tmc_read_prepare_etr(struct tmc_drvdata *drvdata)
goto out;
}
drvdata->reading = true;
/* Disable the TMC if we are trying to read from a running session. */
if (drvdata->mode == CS_MODE_SYSFS) {
spin_unlock_irqrestore(&drvdata->spinlock, flags);
mutex_unlock(&drvdata->mem_lock);
coresight_disable_all_source_link();
mutex_lock(&drvdata->mem_lock);
spin_lock_irqsave(&drvdata->spinlock, flags);
__tmc_etr_disable_hw(drvdata);
}
drvdata->reading = true;
out:
spin_unlock_irqrestore(&drvdata->spinlock, flags);
mutex_unlock(&drvdata->mem_lock);
@ -2199,10 +2203,6 @@ int tmc_read_unprepare_etr(struct tmc_drvdata *drvdata)
* be NULL.
*/
__tmc_etr_enable_hw(drvdata);
spin_unlock_irqrestore(&drvdata->spinlock, flags);
coresight_enable_all_source_link();
spin_lock_irqsave(&drvdata->spinlock, flags);
} else {
/*
* The ETR is not tracing and the buffer was just read.
@ -2219,5 +2219,9 @@ int tmc_read_unprepare_etr(struct tmc_drvdata *drvdata)
tmc_etr_free_sysfs_buf(sysfs_buf);
mutex_unlock(&drvdata->mem_lock);
if (drvdata->mode == CS_MODE_SYSFS)
coresight_enable_all_source_link();
return 0;
}