Messages in this thread | | | Date | Mon, 1 Jun 2020 14:52:44 +0100 | From | Daniel Thompson <> | Subject | Re: [PATCH] kgdb: Don't call the deinit under spinlock |
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On Tue, May 26, 2020 at 02:20:06PM -0700, Douglas Anderson wrote: > When I combined kgdboc_earlycon with an inflight patch titled ("soc: > qcom-geni-se: Add interconnect support to fix earlycon crash") [1] > things went boom. Specifically I got a crash during the transition > between kgdboc_earlycon and the main kgdboc that looked like this: > > Call trace: > <snip> > ... > > The problem was that we were holding the "kgdb_registration_lock" > while calling into code that didn't expect to be called in spinlock > context. > > Let's slightly defer when we call the deinit code so that it's not > done under spinlock. > > NOTE: this does mean that the "deinit" call of the old kgdb IO module > is now made _after_ the init of the new IO module, but presumably > that's OK. > > [1] https://lkml.kernel.org/r/1588919619-21355-3-git-send-email-akashast@codeaurora.org > > Fixes: 220995622da5 ("kgdboc: Add kgdboc_earlycon to support early kgdb using boot consoles") > Signed-off-by: Douglas Anderson <dianders@chromium.org>
Just found this in my inbox... which suggested I forgot to post an "Applied" last week when I pushed it for linux-next.
Expect the kgdb PR for this cycle shortly!
Daniel.
> --- > > kernel/debug/debug_core.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > diff --git a/kernel/debug/debug_core.c b/kernel/debug/debug_core.c > index 4d59aa907fdc..ef94e906f05a 100644 > --- a/kernel/debug/debug_core.c > +++ b/kernel/debug/debug_core.c > @@ -1089,7 +1089,6 @@ int kgdb_register_io_module(struct kgdb_io *new_dbg_io_ops) > } > pr_info("Replacing I/O driver %s with %s\n", > old_dbg_io_ops->name, new_dbg_io_ops->name); > - old_dbg_io_ops->deinit(); > } > > if (new_dbg_io_ops->init) { > @@ -1104,8 +1103,10 @@ int kgdb_register_io_module(struct kgdb_io *new_dbg_io_ops) > > spin_unlock(&kgdb_registration_lock); > > - if (old_dbg_io_ops) > + if (old_dbg_io_ops) { > + old_dbg_io_ops->deinit(); > return 0; > + } > > pr_info("Registered I/O driver %s\n", new_dbg_io_ops->name); > > -- > 2.27.0.rc0.183.gde8f92d652-goog >
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