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The PR is created for demonstrating a potential trace issue: if we try to use trace_xx() to print out logs before the trace is initialized, the FW will crash and we will see "firmware boot failure" from the dmesg.

@marc-hb FYI.

Hold the dma-trace lock when performing on/off switching, to make sure
the status is consistent.

Signed-off-by: Keyon Jie <yang.jie@linux.intel.com>
As there is trace calling in the dma_trace_on/off() internal, we should
not do that with trace->lock held, to avoid deadlock.

Signed-off-by: Keyon Jie <yang.jie@linux.intel.com>
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marc-hb commented Sep 14, 2021

I'm not sure what this proved. #4759 finally demonstrates the issue, thanks.

marc-hb added a commit to marc-hb/sof that referenced this pull request Sep 14, 2021
This reverts commit 7df3674.

This restores the ability to use CONFIG_TRACEM (copy everything to
mailbox) without crashing, in other words it fixes thesofproject#4699

This also fixes the other DSP panic thesofproject#4676 and removes the need for
logical changes in thesofproject#4678, which can be reverted too.

commit 7df3674 ("trace: enable trace after it is ready") was meant
to fix a crash when tr_xxx() was used early. However I've used very
early tracing for months and it never caused any crash (see thesofproject#4334)

I tried adding a tr_err() statement immediately after trace_init(sof) in
primary_core_init() and it works just fine. primary_core_init() runs
extremely early so I don't think it's too demanding not to use an
tr_XXX() before the trace even exists.

The reverted commits confused initializing and enabling.

Reproduction thesofproject#4683 did not seem to demonstrate anything obvious,
there's not even a link to a failed test run. I don't understand how
playing with spin locks is relevant to this.

Later, reproduction thesofproject#4759 finally demonstrated the real issue: through
DEBUG_TRACE_PTR(), some tr_XXX() can indeed be called (in very unusal
debug circumstances specific to the original author) before the trace is
initialized. The previous commit in this series fixes that by simply
guarding it with if(trace_get())

     --------

I am _not_ pretending that these reverts make the tracing code bug-free
and perfect again, absolutely not and very far from it. I'm merely
saying that:

- The first reverted commit caused at least two regressions: thesofproject#4676 and
  thesofproject#4699

- These two commits added yet another variable (time) in an already
  complex situation with an already existing combinatorial "explosion":
  compile-time Kconfigs, run-time settings, platform-specific bugs
  (thesofproject#4333, thesofproject#4573, ...), various races, mbox + DMA, different DMA engines,
  Zephyr vs XTOS, etc.

- Last but not least, we don't want to invest in making the exist trace
  implementation better. We want to switch to the Zephyr implementation
  instead

So let's go back to a previous known good state, I mean _relatively_
good and stay there if we can.

Signed-off-by: Marc Herbert <marc.herbert@intel.com>
lgirdwood pushed a commit that referenced this pull request Sep 15, 2021
This reverts commit 7df3674.

This restores the ability to use CONFIG_TRACEM (copy everything to
mailbox) without crashing, in other words it fixes #4699

This also fixes the other DSP panic #4676 and removes the need for
logical changes in #4678, which can be reverted too.

commit 7df3674 ("trace: enable trace after it is ready") was meant
to fix a crash when tr_xxx() was used early. However I've used very
early tracing for months and it never caused any crash (see #4334)

I tried adding a tr_err() statement immediately after trace_init(sof) in
primary_core_init() and it works just fine. primary_core_init() runs
extremely early so I don't think it's too demanding not to use an
tr_XXX() before the trace even exists.

The reverted commits confused initializing and enabling.

Reproduction #4683 did not seem to demonstrate anything obvious,
there's not even a link to a failed test run. I don't understand how
playing with spin locks is relevant to this.

Later, reproduction #4759 finally demonstrated the real issue: through
DEBUG_TRACE_PTR(), some tr_XXX() can indeed be called (in very unusal
debug circumstances specific to the original author) before the trace is
initialized. The previous commit in this series fixes that by simply
guarding it with if(trace_get())

     --------

I am _not_ pretending that these reverts make the tracing code bug-free
and perfect again, absolutely not and very far from it. I'm merely
saying that:

- The first reverted commit caused at least two regressions: #4676 and
  #4699

- These two commits added yet another variable (time) in an already
  complex situation with an already existing combinatorial "explosion":
  compile-time Kconfigs, run-time settings, platform-specific bugs
  (#4333, #4573, ...), various races, mbox + DMA, different DMA engines,
  Zephyr vs XTOS, etc.

- Last but not least, we don't want to invest in making the exist trace
  implementation better. We want to switch to the Zephyr implementation
  instead

So let's go back to a previous known good state, I mean _relatively_
good and stay there if we can.

Signed-off-by: Marc Herbert <marc.herbert@intel.com>
marc-hb added a commit to marc-hb/sof that referenced this pull request Sep 21, 2021
This reverts commit 7df3674.

This restores the ability to use CONFIG_TRACEM (copy everything to
mailbox) without crashing, in other words it fixes thesofproject#4699

This also fixes the other DSP panic thesofproject#4676 and removes the need for
logical changes in thesofproject#4678, which can be reverted too.

commit 7df3674 ("trace: enable trace after it is ready") was meant
to fix a crash when tr_xxx() was used early. However I've used very
early tracing for months and it never caused any crash (see thesofproject#4334)

I tried adding a tr_err() statement immediately after trace_init(sof) in
primary_core_init() and it works just fine. primary_core_init() runs
extremely early so I don't think it's too demanding not to use an
tr_XXX() before the trace even exists.

The reverted commits confused initializing and enabling.

Reproduction thesofproject#4683 did not seem to demonstrate anything obvious,
there's not even a link to a failed test run. I don't understand how
playing with spin locks is relevant to this.

Later, reproduction thesofproject#4759 finally demonstrated the real issue: through
DEBUG_TRACE_PTR(), some tr_XXX() can indeed be called (in very unusal
debug circumstances specific to the original author) before the trace is
initialized. The previous commit in this series fixes that by simply
guarding it with if(trace_get())

     --------

I am _not_ pretending that these reverts make the tracing code bug-free
and perfect again, absolutely not and very far from it. I'm merely
saying that:

- The first reverted commit caused at least two regressions: thesofproject#4676 and
  thesofproject#4699

- These two commits added yet another variable (time) in an already
  complex situation with an already existing combinatorial "explosion":
  compile-time Kconfigs, run-time settings, platform-specific bugs
  (thesofproject#4333, thesofproject#4573, ...), various races, mbox + DMA, different DMA engines,
  Zephyr vs XTOS, etc.

- Last but not least, we don't want to invest in making the exist trace
  implementation better. We want to switch to the Zephyr implementation
  instead

So let's go back to a previous known good state, I mean _relatively_
good and stay there if we can.

Signed-off-by: Marc Herbert <marc.herbert@intel.com>
(cherry picked from commit f2c13f5)
keyonjie pushed a commit that referenced this pull request Nov 2, 2021
This reverts commit 7df3674.

This restores the ability to use CONFIG_TRACEM (copy everything to
mailbox) without crashing, in other words it fixes #4699

This also fixes the other DSP panic #4676 and removes the need for
logical changes in #4678, which can be reverted too.

commit 7df3674 ("trace: enable trace after it is ready") was meant
to fix a crash when tr_xxx() was used early. However I've used very
early tracing for months and it never caused any crash (see #4334)

I tried adding a tr_err() statement immediately after trace_init(sof) in
primary_core_init() and it works just fine. primary_core_init() runs
extremely early so I don't think it's too demanding not to use an
tr_XXX() before the trace even exists.

The reverted commits confused initializing and enabling.

Reproduction #4683 did not seem to demonstrate anything obvious,
there's not even a link to a failed test run. I don't understand how
playing with spin locks is relevant to this.

Later, reproduction #4759 finally demonstrated the real issue: through
DEBUG_TRACE_PTR(), some tr_XXX() can indeed be called (in very unusal
debug circumstances specific to the original author) before the trace is
initialized. The previous commit in this series fixes that by simply
guarding it with if(trace_get())

     --------

I am _not_ pretending that these reverts make the tracing code bug-free
and perfect again, absolutely not and very far from it. I'm merely
saying that:

- The first reverted commit caused at least two regressions: #4676 and
  #4699

- These two commits added yet another variable (time) in an already
  complex situation with an already existing combinatorial "explosion":
  compile-time Kconfigs, run-time settings, platform-specific bugs
  (#4333, #4573, ...), various races, mbox + DMA, different DMA engines,
  Zephyr vs XTOS, etc.

- Last but not least, we don't want to invest in making the exist trace
  implementation better. We want to switch to the Zephyr implementation
  instead

So let's go back to a previous known good state, I mean _relatively_
good and stay there if we can.

Signed-off-by: Marc Herbert <marc.herbert@intel.com>
(cherry picked from commit f2c13f5)
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2 participants