On Wed, 2019-07-31 at 14:24 +0800, Fuqian Huang wrote: > In drivers/gpu/drm/amd/amdgpu/amdgpu_ih.c, > amdgpu_ih_process calls DRM_DEBUG which calls drm_dbg and > finally calls printk. > As amdgpu_ih_process is called from an interrupt handler, > and interrupt handler should be short as possible. > > As printk may lead to bogging down the system or can even > create a live lock. printk should not be used in IRQ context. > Instead, trace_printk is recommended in IRQ context. > Link: https://lwn.net/Articles/365835 > > Reviewed-by: Joe Perches <joe@xxxxxxxxxxx> I made a suggestion. I did not review this. Please do not add signatures like this if not specifically given by someone. > Signed-off-by: Fuqian Huang <huangfq.daxian@xxxxxxxxx> > --- > Changes in v2: > - Only make the interrupt uses the trace_printk to avoid > all 4000+ drm_dbg/DRM_DEBUG uses emitting a trace_printk. > > drivers/gpu/drm/drm_print.c | 10 +++++++--- > 1 file changed, 7 insertions(+), 3 deletions(-) > > diff --git a/drivers/gpu/drm/drm_print.c b/drivers/gpu/drm/drm_print.c > index a17c8a14dba4..747835d16fa6 100644 > --- a/drivers/gpu/drm/drm_print.c > +++ b/drivers/gpu/drm/drm_print.c > @@ -236,9 +236,13 @@ void drm_dbg(unsigned int category, const char *format, ...) > vaf.fmt = format; > vaf.va = &args; > > - printk(KERN_DEBUG "[" DRM_NAME ":%ps] %pV", > - __builtin_return_address(0), &vaf); > - > + if (in_interrupt()) { > + trace_printk(KERN_DEBUG "[" DRM_NAME ":%ps] %pV", > + __builtin_return_address(0), &vaf); > + } else { > + printk(KERN_DEBUG "[" DRM_NAME ":%ps] %pV", > + __builtin_return_address(0), &vaf); > + } > va_end(args); > } > EXPORT_SYMBOL(drm_dbg); _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
