Messages in this thread | | | Subject | Re: [PATCH] drm: use trace_printk rather than printk in drm_dbg. | From | Joe Perches <> | Date | Tue, 30 Jul 2019 23:06:22 -0700 |
| |
On Wed, 2019-07-31 at 10:45 +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. > Link: https://lwn.net/Articles/365835 [] > diff --git a/drivers/gpu/drm/drm_print.c b/drivers/gpu/drm/drm_print.c [] > @@ -236,7 +236,7 @@ void drm_dbg(unsigned int category, const char *format, ...) > vaf.fmt = format; > vaf.va = &args; > > - printk(KERN_DEBUG "[" DRM_NAME ":%ps] %pV", > + trace_printk(KERN_DEBUG "[" DRM_NAME ":%ps] %pV", > __builtin_return_address(0), &vaf); > > va_end(args);
This makes all 4000+ drm_dbg/DRM_DEBUG uses emit a trace_printk.
I suggest instead you make only the interrupt uses use a different function and not drm_dbg.
Or maybe add an in_interrupt() check like
if (in_interrupt()) printk(KERN_DEBUG etc...) else trace_printk(etc...)
| |