On Mon, Sep 01, 2014 at 04:11:43PM +0200, David Herrmann wrote:
Hi
On Sat, Aug 9, 2014 at 8:22 AM, Chris Wilson chris@chris-wilson.co.uk wrote:
Showing who is the current master is useful for trying to decypher errors when trying to acquire master (e.g. a race with X taking over from plymouth). By including the process name as well as the pid simplifies the task of grabbing enough information remotely at the point of error.
Signed-off-by: Chris Wilson chris@chris-wilson.co.uk
drivers/gpu/drm/drm_info.c | 17 ++++++++++++----- 1 file changed, 12 insertions(+), 5 deletions(-)
diff --git a/drivers/gpu/drm/drm_info.c b/drivers/gpu/drm/drm_info.c index 15ec9f4..d813430 100644 --- a/drivers/gpu/drm/drm_info.c +++ b/drivers/gpu/drm/drm_info.c @@ -184,14 +184,21 @@ int drm_clients_info(struct seq_file *m, void *data) struct drm_file *priv;
mutex_lock(&dev->struct_mutex);
seq_printf(m, "a dev pid uid magic\n\n");list_for_each_entry(priv, &dev->filelist, lhead) {seq_printf(m, "%c %3d %5d %5d %10u\n",priv->authenticated ? 'y' : 'n',priv->minor->index,
seq_printf(m, " pid dev master a uid magic\n");Maybe mention "task" here? Or is this supposed to be a logical part of "pid"?
Yeah, I was thinking that comm/pid were essentially the same column. Top uses command which would be reasonable to reuse.
list_for_each_entry_reverse(priv, &dev->filelist, lhead) {No idea why you do backwards traversal, but ok..
Clients are added youngest-first. So traversing backwards gives kernel X/display manager clients
struct task_struct *task;rcu_read_lock();What's that rcu-lock for? task->comm is pre-allocated, priv->pid is static, kuid... no idea?
Cargo-culting the locking from the discussion with Tetsuo:
commit 3ec2f427e6f82b9b8f9b18dd2c758b864385df39 Author: Tetsuo Handa penguin-kernel@I-love.SAKURA.ne.jp Date: Fri Jan 3 20:42:18 2014 +0900
drm/i915: Fix refcount leak and possible NULL pointerdereference.
Since get_pid_task() grabs a reference on the task_struct, we have to drop the refcount after reading that task's comm name. Use pid_task() with RCU instead.
Also, avoid directly reading like pid_task()->comm because pid_task() will return NULL if the task have already exit()ed.
This patch fixes both problems.
Anyway, patch looks good otherwise. Especially task->comm sounds really handy in that list.
It was. Thanks for the feedback, will add the extra header and comment. -Chris