On 12/06/15 19:05, Derek Foreman wrote:
> On 12/06/15 11:29 AM, Emil Velikov wrote:
>> Hi Derek,
>
> Hi, thanks for looking at this. :)
>
Props goes to Matt, for the reminder. It kind of fell of my radar.
>> On 1 May 2015 at 18:34, Derek Foreman <der...@osg.samsung.com> wrote:
>>> These fds can propagate to child processes if we don't set CLOEXEC,
>>> so make a best effort to do that.
>>>
>>> Signed-off-by: Derek Foreman <der...@osg.samsung.com>
>>> ---
>>> Noticed this when fixing up similar problems in weston - weston's
>>> drm fd gets dup()ed here and loses CLOEXEC and ends up in every child
>>> process the shell launches.
>>>
>>> src/egl/drivers/dri2/platform_drm.c | 14 +++++++++++---
>>> 1 file changed, 11 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/src/egl/drivers/dri2/platform_drm.c
>>> b/src/egl/drivers/dri2/platform_drm.c
>>> index 486b003..c326d6c 100644
>>> --- a/src/egl/drivers/dri2/platform_drm.c
>>> +++ b/src/egl/drivers/dri2/platform_drm.c
>>> @@ -596,7 +596,11 @@ dri2_initialize_drm(_EGLDriver *drv, _EGLDisplay *disp)
>>> struct dri2_egl_display *dri2_dpy;
>>> struct gbm_device *gbm;
>>> int fd = -1;
>>> - int i;
>>> + int i, flags = O_RDWR;
>>> +
>>> +#ifdef O_CLOEXEC
>>> + flags |= O_CLOEXEC;
>>> +#endif
>>>
>>> loader_set_logger(_eglLog);
>>>
>>> @@ -611,9 +615,9 @@ dri2_initialize_drm(_EGLDriver *drv, _EGLDisplay *disp)
>>> char buf[64];
>>> int n = snprintf(buf, sizeof(buf), DRM_DEV_NAME, DRM_DIR_NAME, 0);
>>> if (n != -1 && n < sizeof(buf))
>>> - fd = open(buf, O_RDWR);
>>> + fd = open(buf, flags);
>>> if (fd < 0)
>>> - fd = open("/dev/dri/card0", O_RDWR);
>>> + fd = open("/dev/dri/card0", flags);
>>> dri2_dpy->own_device = 1;
>>> gbm = gbm_create_device(fd);
>>> if (gbm == NULL)
>>> @@ -639,6 +643,10 @@ dri2_initialize_drm(_EGLDriver *drv, _EGLDisplay *disp)
>>> }
>>> }
>>>
>>> + flags = fcntl(dri2_dpy->fd, F_GETFD);
>>> + if (flags >= 0 && !(flags & FD_CLOEXEC))
>>> + fcntl(fd, F_SETFD, flags | FD_CLOEXEC);
>>> +
>> In other places in mesa we explicitly check for EINVAL if open()
>> fails, and use that as indication that O_CLOEXEC is not supported
>> (note that we only use the O_RDWR and O_CLOEXEC flags). Curious which
>> would be the better approach to use through mesa ?
>
> Oops - I think that way is better.
>
> There's a simple function in loader.c called drm_open_device() that does
> the open that way, could we just rename that to loader_open_device() and
> make it non-static and call it from dri2_initialize_drm()?
>
That's exactly what I was thinking actually :-)
> That said...
>
> Unfortunately, it appears my previous testing was insufficient and
> there's still a leaked fd - dup() creates fds without CLOEXEC set.
>
Seems that we ignore that in a few places through mesa - how about we
replace dup() + fcntl(F_SETFD, fcntl(F_GETFD)|FD_CLOEXEC) with
fcntl(F_DUPFD_CLOEXEC) ?
Its requirements are almost the same as O_CLOEXEC (kernel 2.6.{23,24}
and glibc 2.7) as opposed to dup2/dup3 which requires glibc 2.9 (not
sure about the kernel).
Cheers,
Emil
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