Re: [PATCH v3] ufs: core: add hba parameter to trace events

["Peter Wang (王信友)" <peter.wang@mediatek.com>]

On Wed, 2026-07-01 at 08:57 -0400, Steven Rostedt wrote:
> On Wed, 1 Jul 2026 06:11:37 +0000
> Peter Wang (王信友) <peter.wang@mediatek.com> wrote:
> 
> > However, I am curious: if the HBA is removed, implying that the
> > storage would become unusable, might the system encounter an
> > I/O hang or shutdown, potentially preventing its detection?
> > Perhaps it's a theoretical issue that would not manifest
> > in a real-world situation?
> 
> Note, it doesn't necessarily mean that the device itself was removed.
> The
> issue is that a pointer to an allocated descriptor is saved in the
> ring buffer.
> 
> Maybe once the device is created it will never go way. But what
> happens if
> for some reason the descriptor is freed and reallocated? Now the old
> descriptor pointer is still in the ring buffer.
> 
> What in the logic guarantees that the pointer will never be freed?
> 
> And lets say there is an issue and the hba is freed and you debug
> this by
> dumping the trace buffer via ftrace_dump_on_oops. Now the dump itself
> may
> crash and you don't have a way to debug what happened.
> 
> One other point that causes issues here. It makes user space tracing
> useless. Try tracing this with "trace-cmd record". These events will
> not be
> able to be parsed.
> 
> -- Steve
> 

Hi Steven,

Thank you for the detailed explanation. I have no further questions.

Thanks
Peter