Re: Crash in msm serial on dragonboard with ftrace bootargs

[Sai Prakash Ranjan]

On 10/17/2018 5:08 PM, Sai Prakash Ranjan wrote:
> > What do you think about the (untested) patch below? It seems to me 
> > that it
> > should solve the issue of missing early crash dumps, but I have not 
> > tested it
> > yet. Sai, would you mind trying it out and let me know if you can see the
> > early crash dumps properly now?
> >
> > ----8<---
> > From: "Joel Fernandes (Google)" <joel@xxxxxxxxxxxxxxxxx>
> > Subject: [RFC] pstore: allocate compression during late_initcall
> >
> > ramoop's pstore registration (using pstore_register) has to run during
> > late_initcall because crypto backend may not be ready during
> > postcore_initcall. This causes missing of dmesg crash dumps which could
> > have been caught by pstore.
> >
> > Instead, lets allow ramoops pstore registration earlier, and once crypto
> > is ready we can initialize the compression.
> >
> > Reported-by: Sai Prakash Ranjan <saiprakash.ranjan@xxxxxxxxxxxxxx>
> > Signed-off-by: Joel Fernandes (Google) <joel@xxxxxxxxxxxxxxxxx>
> > ---
> > Â fs/pstore/platform.c | 13 +++++++++++++
> > Â fs/pstore/ram.cÂÂÂÂÂ |Â 2 +-
> > Â 2 files changed, 14 insertions(+), 1 deletion(-)
> >
> > diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
> > index 15e99d5a681d..f09066db2d4d 100644
> > --- a/fs/pstore/platform.c
> > +++ b/fs/pstore/platform.c
> > @@ -780,6 +780,19 @@ void __init pstore_choose_compression(void)
> > ÂÂÂÂÂ }
> > Â }
> > +static int __init pstore_compression_late_init(void)
> > +{
> > +ÂÂÂ /*
> > +ÂÂÂÂ * Check if any pstore backends registered earlier but did not 
> > allocate
> > +ÂÂÂÂ * for compression because crypto was not ready, if so then 
> > initialize
> > +ÂÂÂÂ * compression.
> > +ÂÂÂÂ */
> > +ÂÂÂ if (psinfo && !tfm)
> > +ÂÂÂÂÂÂÂ allocate_buf_for_compression();
> > +ÂÂÂ return 0;
> > +}
> > +late_initcall(pstore_compression_late_init);
> > +
> > Â module_param(compress, charp, 0444);
> > Â MODULE_PARM_DESC(compress, "Pstore compression to use");
> > diff --git a/fs/pstore/ram.c b/fs/pstore/ram.c
> > index bbd1e357c23d..98e48d1a9776 100644
> > --- a/fs/pstore/ram.c
> > +++ b/fs/pstore/ram.c
> > @@ -940,7 +940,7 @@ static int __init ramoops_init(void)
> > ÂÂÂÂÂ ramoops_register_dummy();
> > ÂÂÂÂÂ return platform_driver_register(&ramoops_driver);
> > Â }
> > -late_initcall(ramoops_init);
> > +postcore_initcall(ramoops_init);
> > Â static void __exit ramoops_exit(void)
> > Â {
>
> Yes I could see the early crash dump. Also I tested with different 
> compression (LZO) instead of deflate just to be sure and it works fine, 
> thanks :)
>
> Tested-by: Sai Prakash Ranjan <saiprakash.ranjan@xxxxxxxxxxxxxx>

I just noticed that allocate_buf_for_compression() is also called from 
pstore_register(). Shouldn't that call be removed now that ramoops_init 
is moved to postcore_initcall and allocate_buf_for_compression() will 
just return doing nothing when called from pstore_register()?

Thanks,
Sai

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