Re: [PATCH 2/3] drm/scheduler: Don't call wait_event_killable for signaled process.

["Michel Dänzer" <michel@daenzer.net>]

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On 2018-05-17 09:05 PM, Andrey Grodzovsky wrote:
> On 05/17/2018 10:48 AM, Michel Dänzer wrote:
>> On 2018-05-17 01:18 PM, Andrey Grodzovsky wrote:
>>> Hi Michele and others, I am trying to implement the approach bellow to
>>> resolve AMDGPU's hang when commands are stuck in pipe during process
>>> exit.
>>>
>>> I noticed that once I implemented the file_operation.flush callback
>>> then during run of X, i see the flush callback gets called not only for
>>> Xorg process but for other
>>>
>>> processes such as 'xkbcomp' and even 'sh', it seems like Xorg passes his
>>> FDs to children, Christian mentioned he remembered a discussion to
>>> always set FD_CLOEXEC flag when opening the hardware device file, so
>>>
>>> we suspect a bug in Xorg with regard to this behavior.
>> Try the libdrm patch below.
>>
>> Note that the X server passes DRM file descriptors to DRI3 clients.
> 
> Tried it, didn't help. I still see other processes calling .flush for
> /dev/dri/card0

Try the attached xserver patch on top. With these patches, I no longer
see any DRM file descriptors being opened without O_CLOEXEC running Xorg
-pogo in strace.


Anyway, the kernel can't rely on userspace using O_CLOEXEC. If the flush
callback being called from multiple processes is an issue, maybe the
flush callback isn't appropriate after all.


-- 
Earthling Michel Dänzer               |               http://www.amd.com
Libre software enthusiast             |             Mesa and X developer

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diff --git a/hw/xfree86/drivers/modesetting/driver.c b/hw/xfree86/drivers/modesetting/driver.c
index 5d8906d63..306541f33 100644
--- a/hw/xfree86/drivers/modesetting/driver.c
+++ b/hw/xfree86/drivers/modesetting/driver.c
@@ -200,12 +200,12 @@ open_hw(const char *dev)
     int fd;
 
     if (dev)
-        fd = open(dev, O_RDWR, 0);
+        fd = open(dev, O_RDWR | O_CLOEXEC, 0);
     else {
         dev = getenv("KMSDEVICE");
-        if ((NULL == dev) || ((fd = open(dev, O_RDWR, 0)) == -1)) {
+        if ((NULL == dev) || ((fd = open(dev, O_RDWR | O_CLOEXEC, 0)) == -1)) {
             dev = "/dev/dri/card0";
-            fd = open(dev, O_RDWR, 0);
+            fd = open(dev, O_RDWR | O_CLOEXEC, 0);
         }
     }
     if (fd == -1)
diff --git a/hw/xfree86/os-support/linux/lnx_platform.c b/hw/xfree86/os-support/linux/lnx_platform.c
index 11af52c46..70374ace8 100644
--- a/hw/xfree86/os-support/linux/lnx_platform.c
+++ b/hw/xfree86/os-support/linux/lnx_platform.c
@@ -43,7 +43,7 @@ get_drm_info(struct OdevAttributes *attribs, char *path, int delayed_index)
     }
 
     if (fd == -1)
-        fd = open(path, O_RDWR, O_CLOEXEC);
+        fd = open(path, O_RDWR | O_CLOEXEC, 0);
 
     if (fd == -1)
         return FALSE;

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