On Fri, 22 Jan 2021 at 15:18, Daniel Thompson <daniel.thomp...@linaro.org> wrote: > > On Fri, Jan 22, 2021 at 03:08:31PM +0530, Sumit Garg wrote: > > Currently kdb uses in_interrupt() to determine whether it's library > > code has been called from the kgdb trap handler or from a saner calling > > context such as driver init. This approach is broken because > > in_interrupt() alone isn't able to determine kgdb trap handler entry via > > normal task context such as [1]. > > > > We can improve this by adding check for in_dbg_master() which explicitly > > determines if we are running in debugger context. Also, use in_atomic() > > instead of in_interrupt() as the former is more appropriate to know atomic > > context and moreover the later one is deprecated. > > Why do we need the in_atomic() here? Or put another way, why isn't > in_dbg_master() sufficient? >
Yes, you are right in_atomic() is redundant after looking at usage of GFP_KDB. Will get rid of it in v2. -Sumit > > Daniel. > > > > > > [1] $ echo g > /proc/sysrq-trigger > > > > Signed-off-by: Sumit Garg <sumit.g...@linaro.org> > > --- > > kernel/debug/kdb/kdb_private.h | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/kernel/debug/kdb/kdb_private.h b/kernel/debug/kdb/kdb_private.h > > index 7a4a181..7a9ebd9 100644 > > --- a/kernel/debug/kdb/kdb_private.h > > +++ b/kernel/debug/kdb/kdb_private.h > > @@ -231,7 +231,7 @@ extern struct task_struct *kdb_curr_task(int); > > > > #define kdb_task_has_cpu(p) (task_curr(p)) > > > > -#define GFP_KDB (in_interrupt() ? GFP_ATOMIC : GFP_KERNEL) > > +#define GFP_KDB (in_atomic() || in_dbg_master() ? GFP_ATOMIC : GFP_KERNEL) > > > > extern void *debug_kmalloc(size_t size, gfp_t flags); > > extern void debug_kfree(void *); > > -- > > 2.7.4 > >