On 11 January 2017 at 21:59, Suzuki K Poulose <Suzuki.Poulose@xxxxxxx> wrote: > On 11/01/17 11:41, Chunyan Zhang wrote: >> >> On 11 January 2017 at 01:36, Mathieu Poirier <mathieu.poirier@xxxxxxxxxx> >> wrote: >>> >>> On Tue, Jan 10, 2017 at 11:21:55AM +0000, Suzuki K Poulose wrote: >>>> >>>> The stm is automatically enabled when an application sets the policy >>>> via ->link() call back by using coresight_enable(), which keeps the >>>> refcount of the current users of the STM. However, the unlink() callback >>>> issues stm_disable() directly, which leaves the STM turned off, without >>>> the coresight layer knowing about it. This prevents any further uses >>>> of the STM hardware as the coresight layer still thinks the STM is >>>> turned on and doesn't issue an stm_enable(). Even manually enabling >>>> the STM via sysfs can't really enable the hw. >>>> >>>> e.g, >>>> >>>> $ echo 1 > $CS_DEVS/$ETR/enable_sink >>>> $ mkdir -p $CONFIG_FS/stp-policy/$source.0/stm_test/ >>>> $ echo 32768 65535 > $CONFIG_FS/stp-policy/$source.0/stm_test/channels >>>> $ echo 64 > $CS_DEVS/$source/traceid >>>> $ ./stm_app >>>> Sending 64000 byte blocks of pattern 0 at 0us intervals >>>> Success to map channel(32768~32783) to 0xffffa95fa000 >>>> Sending on channel 32768 >>>> $ dd if=/dev/$ETR of=~/trace.bin.1 >>>> 597+1 records in >>>> 597+1 records out >>>> 305920 bytes (306 kB) copied, 0.399952 s, 765 kB/s >>>> $ ./stm_app >>>> Sending 64000 byte blocks of pattern 0 at 0us intervals >>>> Success to map channel(32768~32783) to 0xffff7e9e2000 >>>> Sending on channel 32768 >>>> $ dd if=/dev/$ETR of=~/trace.bin.2 >>>> 0+0 records in >>>> 0+0 records out >>>> 0 bytes (0 B) copied, 0.0232083 s, 0.0 kB/s >>>> >>>> Note that we don't get any data from the ETR for the second session. >>>> >>>> Also dmesg shows : >>>> >>>> [ 77.520458] coresight-tmc 20800000.etr: TMC-ETR enabled >>>> [ 77.537097] coresight-replicator etr_replicator@20890000: REPLICATOR >>>> enabled >>>> [ 77.558828] coresight-replicator main_replicator@208a0000: REPLICATOR >>>> enabled >>>> [ 77.581068] coresight-funnel 208c0000.main_funnel: FUNNEL inport 0 >>>> enabled >>>> [ 77.602217] coresight-tmc 20840000.etf: TMC-ETF enabled >>>> [ 77.618422] coresight-stm 20860000.stm: STM tracing enabled >>>> [ 139.554252] coresight-stm 20860000.stm: STM tracing disabled >>>> # End of first tracing session >>>> [ 146.351135] coresight-tmc 20800000.etr: TMC read start >>>> [ 146.514486] coresight-tmc 20800000.etr: TMC read end >>>> # Note that the STM is not turned on via >>>> stm_generic_link()->coresight_enable() >>>> # and hence none of the components are turned on. >>>> [ 152.479080] coresight-tmc 20800000.etr: TMC read start >>>> [ 152.542632] coresight-tmc 20800000.etr: TMC read end >>>> >>>> This patch balances the unlink operation by using the >>>> coresight_disable(), >>>> keeping the coresight layer in sync with the hardware state. >>>> >>>> Fixes: commit 237483aa5cf43 ("coresight: stm: adding driver for >>>> CoreSight STM component") >>>> Cc: Pratik Patel <pratikp@xxxxxxxxxxxxxx> >>>> Cc: Mathieu Poirier <mathieu.poirier@xxxxxxxxxx> >>>> Cc: Chunyan Zhang <zhang.chunyan@xxxxxxxxxx> >>>> Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> >>>> Cc: stable@xxxxxxxxxxxxxxx # 4.7+ >>>> Reported-by: Robert Walker <robert.walker@xxxxxxx> >>>> Signed-off-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx> >>>> --- >>>> drivers/hwtracing/coresight/coresight-stm.c | 2 +- >>>> 1 file changed, 1 insertion(+), 1 deletion(-) >>>> >>>> diff --git a/drivers/hwtracing/coresight/coresight-stm.c >>>> b/drivers/hwtracing/coresight/coresight-stm.c >>>> index 3524452..57b7330 100644 >>>> --- a/drivers/hwtracing/coresight/coresight-stm.c >>>> +++ b/drivers/hwtracing/coresight/coresight-stm.c >>>> @@ -356,7 +356,7 @@ static void stm_generic_unlink(struct stm_data >>>> *stm_data, >>>> if (!drvdata || !drvdata->csdev) >>>> return; >>>> >>>> - stm_disable(drvdata->csdev, NULL); >>>> + coresight_disable(drvdata->csdev); >>> >>> >>> This looks valid to me. >>> >>> Chunyan, any reason to use stm_disable() directly rather than calling it >>> as part >>> of the device OPS in coresight_disable()? >> >> >> I don't think there's some special reason for this. I simply hadn't >> noticed that these two operations didn't use two balanced functions. > > > Please can I have an Ack/Reviewed -by on it, so that we can push it > as a fix. Sure, I've had a run with this patch, it works well, so, Reviewed-by: Chunyan Zhang <zhang.chunyan@xxxxxxxxxx> Thanks, Chunyan > > > Suzuki > -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html