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  1. 26 Mar, 2020 3 commits
    • Daniel Vetter's avatar
      drm: add managed resources tied to drm_device · c6603c74
      Daniel Vetter authored 
      We have lots of these. And the cleanup code tends to be of dubious
quality. The biggest wrong pattern is that developers use devm_, which
ties the release action to the underlying struct device, whereas
all the userspace visible stuff attached to a drm_device can long
outlive that one (e.g. after a hotunplug while userspace has open
files and mmap'ed buffers). Give people what they want, but with more
correctness.

Mostly copied from devres.c, with types adjusted to fit drm_device and
a few simplifications - I didn't (yet) copy over everything. Since
the types don't match code sharing looked like a hopeless endeavour.

For now it's only super simplified, no groups, you can't remove
actions (but kfree exists, we'll need that soon). Plus all specific to
drm_device ofc, including the logging. Which I didn't bother to make
compile-time optional, since none of the other drm logging is compile
time optional either.

One tricky bit here is the chicken&egg between allocating your
drm_device structure and initiliazing it with drm_dev_init. For
perfect onion unwinding we'd need to have the action to kfree the
allocation registered before drm_dev_init registers any of its own
release handlers. But drm_dev_init doesn't know where exactly the
drm_device is emebedded into the overall structure, and by the time it
returns it'll all be too late. And forcing drivers to be able clean up
everything except the one kzalloc is silly.

Work around this by having a very special final_kfree pointer. This
also avoids troubles with the list head possibly disappearing from
underneath us when we release all resources attached to the
drm_device.

v2: Do all the kerneldoc at the end, to avoid lots of fairly pointless
shuffling while getting everything into shape.

v3: Add static to add/del_dr (Neil)
Move typo fix to the right patch (Neil)

v4: Enforce contract for drmm_add_final_kfree:

Use ksize() to check that the drm_device is indeed contained somewhere
in the final kfree(). Because we need that or the entire managed
release logic blows up in a pile of use-after-frees. Motivated by a
discussion with Laurent.

v5: Review from Laurent:
- %zu instead of casting size_t
- header guards
- sorting of includes
- guarding of data assignment if we didn't allocate it for a NULL
  pointer
- delete spurious newline
- cast void* data parameter correctly in ->release call, no idea how
  this even worked before

v6: Review from Sam
- Add the kerneldoc for the managed sub-struct back in, even if it
  doesn't show up in the generated html somehow.
- Explain why __always_inline.
- Fix bisectability around the final kfree() in drm_dev_relase(). This
  is just interim code which will disappear again.
- Some whitespace polish.
- Add debug output when drmm_add_action or drmm_kmalloc fail.

v7: My bisectability fix wasn't up to par as noticed by smatch.

v8: Remove unecessary {} around if else

v9: Use kstrdup_const, which requires kfree_const and introducing a free_dr()
helper (Thomas).

v10: kfree_const goes boom on the plain "kmalloc" assignment, somehow
we need to wrap that in kstrdup_const() too!! Also renumber revision
log, I somehow reset it midway thruh.
Reviewed-by: default avatarSam Ravnborg <sam@ravnborg.org>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Neil Armstrong <narmstrong@baylibre.com
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Signed-off-by: default avatarDaniel Vetter <daniel.vetter@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200324124540.3227396-1-daniel.vetter@ffwll.ch
      c6603c74
    • Daniel Vetter's avatar
      drm/i915: Don't clear drvdata in ->release · 0ce542f7
      Daniel Vetter authored 
      For two reasons:

- The driver core clears this already for us after we're unloaded in
  __device_release_driver().

- It's way too late, the drm_device ->release callback might massively
  outlive the underlying physical device, since a drm_device can be
  kept alive by open drm_file or well really anything else userspace
  is still hanging onto. So if we clear this ourselves, we should
  clear it in the pci ->remove callback, not in the drm_device
  ->release callback.

Looking at git history this was fixed in the driver core with

commit 0998d063
Author: Hans de Goede <hdegoede@redhat.com>
Date:   Wed May 23 00:09:34 2012 +0200

    device-core: Ensure drvdata = NULL when no driver is bound

v2: Cite the core fix in the commit message (Chris).

v3: Fix commit message and unused variable warning (Jani).

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: default avatarJani Nikula <jani.nikula@intel.com>
Signed-off-by: default avatarDaniel Vetter <daniel.vetter@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200323144950.3018436-3-daniel.vetter@ffwll.ch
      0ce542f7
    • Daniel Vetter's avatar
      mm/sl[uo]b: export __kmalloc_track(_node)_caller · fd7cb575
      Daniel Vetter authored 
      slab does this already, and I want to use this in a memory allocation
tracker in drm for stuff that's tied to the lifetime of a drm_device,
not the underlying struct device. Kinda like devres, but for drm.
Acked-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarDaniel Vetter <daniel.vetter@intel.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-mm@kvack.org
Link: https://patchwork.freedesktop.org/patch/msgid/20200323144950.3018436-2-daniel.vetter@ffwll.ch
      fd7cb575
  3. 24 Mar, 2020 7 commits
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  13. 19 Mar, 2020 1 commit
  15. 18 Mar, 2020 10 commits
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