[v2,00/23] interconnect: fix racy provider registration

Message

Johan Hovold March 6, 2023, 7:56 a.m. UTC

The current interconnect provider interface is inherently racy as
providers are expected to be registered before being fully initialised.

This can specifically cause racing DT lookups to fail as I recently
noticed when the Qualcomm cpufreq driver failed to probe:

	of_icc_xlate_onecell: invalid index 0
        cpu cpu0: error -EINVAL: error finding src node
        cpu cpu0: dev_pm_opp_of_find_icc_paths: Unable to get path0: -22
        qcom-cpufreq-hw: probe of 18591000.cpufreq failed with error -22

This only happens very rarely, but the bug is easily reproduced by
increasing the race window by adding an msleep() after registering
osm-l3 interconnect provider.

Note that the Qualcomm cpufreq driver is especially susceptible to this
race as the interconnect path is looked up from the CPU nodes so that
driver core does not guarantee the probe order even when device links
are enabled (which they not always are).

This series adds a new interconnect provider registration API which is
used to fix up the interconnect drivers before removing the old racy
API.

Included are also a number of fixes for other bugs found while preparing
the series.

Johan


Changes in v2
 - icc_node_destroy() can be called with an arbitrary node id so add the
   missing sanity check to handle potential attempts to destroy a
   non-existing node (patch 01/23). Reported by Dan Carpenter and the
   kernel test robot:

   https://lore.kernel.org/oe-kbuild/[e-mail]/


Johan Hovold (23):
  interconnect: fix mem leak when freeing nodes
  interconnect: fix icc_provider_del() error handling
  interconnect: fix provider registration API
  interconnect: imx: fix registration race
  interconnect: qcom: osm-l3: fix registration race
  interconnect: qcom: rpm: fix probe child-node error handling
  interconnect: qcom: rpm: fix probe PM domain error handling
  interconnect: qcom: rpm: fix registration race
  interconnect: qcom: rpmh: fix probe child-node error handling
  interconnect: qcom: rpmh: fix registration race
  interconnect: qcom: msm8974: fix registration race
  interconnect: qcom: sm8450: fix registration race
  interconnect: qcom: sm8550: fix registration race
  interconnect: exynos: fix node leak in probe PM QoS error path
  interconnect: exynos: fix registration race
  interconnect: exynos: drop redundant link destroy
  memory: tegra: fix interconnect registration race
  memory: tegra124-emc: fix interconnect registration race
  memory: tegra20-emc: fix interconnect registration race
  memory: tegra30-emc: fix interconnect registration race
  interconnect: drop racy registration API
  interconnect: drop unused icc_get() interface
  interconnect: drop unused icc_link_destroy() interface

 drivers/interconnect/core.c           | 152 +++++---------------------
 drivers/interconnect/imx/imx.c        |  20 ++--
 drivers/interconnect/qcom/icc-rpm.c   |  33 +++---
 drivers/interconnect/qcom/icc-rpmh.c  |  30 +++--
 drivers/interconnect/qcom/msm8974.c   |  20 ++--
 drivers/interconnect/qcom/osm-l3.c    |  14 +--
 drivers/interconnect/qcom/sm8450.c    |  22 ++--
 drivers/interconnect/qcom/sm8550.c    |  22 ++--
 drivers/interconnect/samsung/exynos.c |  30 ++---
 drivers/memory/tegra/mc.c             |  16 ++-
 drivers/memory/tegra/tegra124-emc.c   |  12 +-
 drivers/memory/tegra/tegra20-emc.c    |  12 +-
 drivers/memory/tegra/tegra30-emc.c    |  12 +-
 include/linux/interconnect-provider.h |  19 ++--
 include/linux/interconnect.h          |   8 --
 15 files changed, 157 insertions(+), 265 deletions(-)