linux.git/drivers/regulator/core.c, branch v5.11

regulator: Fix lockdep warning resolving supplies

2021-01-22T14:03:07+00:00

With commit eaa7995c529b54 (regulator: core: avoid
regulator_resolve_supply() race condition) we started holding the rdev
lock while resolving supplies, an operation that requires holding the
regulator_list_mutex. This results in lockdep warnings since in other
places we take the list mutex then the mutex on an individual rdev.

Since the goal is to make sure that we don't call set_supply() twice
rather than a concern about the cost of resolution pull the rdev lock
and check for duplicate resolution down to immediately before we do the
set_supply() and drop it again once the allocation is done.

Fixes: eaa7995c529b54 (regulator: core: avoid regulator_resolve_supply() race condition)
Reported-by: Marek Szyprowski 
Tested-by: Marek Szyprowski 
Signed-off-by: Mark Brown 
Link: https://lore.kernel.org/r/20210122132042.10306-1-broonie@kernel.org
Signed-off-by: Mark Brown

regulator: core: avoid regulator_resolve_supply() race condition

2021-01-08T18:22:59+00:00

The final step in regulator_register() is to call
regulator_resolve_supply() for each registered regulator
(including the one in the process of being registered).  The
regulator_resolve_supply() function first checks if rdev->supply
is NULL, then it performs various steps to try to find the supply.
If successful, rdev->supply is set inside of set_supply().

This procedure can encounter a race condition if two concurrent
tasks call regulator_register() near to each other on separate CPUs
and one of the regulators has rdev->supply_name specified.  There
is currently nothing guaranteeing atomicity between the rdev->supply
check and set steps.  Thus, both tasks can observe rdev->supply==NULL
in their regulator_resolve_supply() calls.  This then results in
both creating a struct regulator for the supply.  One ends up
actually stored in rdev->supply and the other is lost (though still
present in the supply's consumer_list).

Here is a kernel log snippet showing the issue:

[   12.421768] gpu_cc_gx_gdsc: supplied by pm8350_s5_level
[   12.425854] gpu_cc_gx_gdsc: supplied by pm8350_s5_level
[   12.429064] debugfs: Directory 'regulator.4-SUPPLY' with parent
               '17a00000.rsc:rpmh-regulator-gfxlvl-pm8350_s5_level'
               already present!

Avoid this race condition by holding the rdev->mutex lock inside
of regulator_resolve_supply() while checking and setting
rdev->supply.

Signed-off-by: David Collins 
Link: https://lore.kernel.org/r/1610068562-4410-1-git-send-email-collinsd@codeaurora.org
Signed-off-by: Mark Brown

Merge remote-tracking branch 'regulator/for-5.11' into regulator-next

2020-12-11T17:48:32+00:00

regulator: core: return zero for selectors lower than linear_min_sel

2020-11-26T13:08:15+00:00

Selectors lower than linear_min_sel should not be considered invalid.
Thus return zero in case _regulator_list_voltage(),
regulator_list_hardware_vsel() or regulator_list_voltage_table()
receives such selectors as argument.

Fixes: bdcd1177578c ("regulator: core: validate selector against linear_min_sel")
Reported-by: Jon Hunter 
Signed-off-by: Claudiu Beznea 
Link: https://lore.kernel.org/r/1606325147-606-1-git-send-email-claudiu.beznea@microchip.com
Signed-off-by: Mark Brown

regulator: core: do not continue if selector match

2020-11-13T18:02:07+00:00

Do not continue if selector has already been located.

Signed-off-by: Claudiu Beznea 
Link: https://lore.kernel.org/r/1605290164-11556-1-git-send-email-claudiu.beznea@microchip.com
Signed-off-by: Mark Brown

Merge series "regulator: mcp16502: add support for ramp delay" from Claudiu Beznea :

2020-11-13T17:09:18+00:00

Hi,

This series adds support for ramp delay on mcp16502. It also adds
some cleanup on mcp16502.

Apart from that patches 1/6 fixes the selector validation in case
the regulator::desc::linear_min_sel is not zero.

Thank you,
Claudiu Beznea

Changes in v3:
- fix compilation error in patch 5/6
  Reported-by: kernel test robot 

Changes in v2:
- rebase on top of regulator/for-next
- checked 1/6 and 3/6 applies on top of regulator/for-5.10

Claudiu Beznea (6):
  regulator: core: validate selector against linear_min_sel
  regulator: core: do not continue if selector match
  regulator: mcp16502: add linear_min_sel
  regulator: mcp16502: adapt for get/set on other registers
  regulator: mcp16502: add support for ramp delay
  regulator: mcp16502: remove void documentation of struct mcp16502

 drivers/regulator/core.c     |  12 +++-
 drivers/regulator/helpers.c  |   3 +-
 drivers/regulator/mcp16502.c | 135 ++++++++++++++++++++++++++++++++++++-------
 3 files changed, 127 insertions(+), 23 deletions(-)

--
2.7.4

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

regulator: core: validate selector against linear_min_sel

2020-11-13T16:13:11+00:00

There are regulators who's min selector is not zero. Selectors loops
(looping b/w zero and regulator::desc::n_voltages) might throw errors
because invalid selectors are used (lower than
regulator::desc::linear_min_sel). For this situations validate selectors
against regulator::desc::linear_min_sel.

Signed-off-by: Claudiu Beznea 
Link: https://lore.kernel.org/r/1605280870-32432-2-git-send-email-claudiu.beznea@microchip.com
Signed-off-by: Mark Brown

regulator: debug early supply resolving

2020-11-13T16:10:05+00:00

Help debugging the case when set_machine_constraints() needs to be
repeated.

Signed-off-by: Michał Mirosław 
Tested-by: Ahmad Fatoum  # stpmic1
Link: https://lore.kernel.org/r/f9cba575580369e46661a9278ee6c6a8d8564c2a.1605226675.git.mirq-linux@rere.qmqm.pl
Signed-off-by: Mark Brown

regulator: workaround self-referent regulators

2020-11-13T14:21:26+00:00

Workaround regulators whose supply name happens to be the same as its
own name. This fixes boards that used to work before the early supply
resolving was removed. The error message is left in place so that
offending drivers can be detected.

Fixes: aea6cb99703e ("regulator: resolve supply after creating regulator")
Cc: stable@vger.kernel.org
Reported-by: Ahmad Fatoum 
Signed-off-by: Michał Mirosław 
Tested-by: Ahmad Fatoum  # stpmic1
Link: https://lore.kernel.org/r/d703acde2a93100c3c7a81059d716c50ad1b1f52.1605226675.git.mirq-linux@rere.qmqm.pl
Signed-off-by: Mark Brown

regulator: avoid resolve_supply() infinite recursion

2020-11-13T14:21:25+00:00

When a regulator's name equals its supply's name the
regulator_resolve_supply() recurses indefinitely. Add a check
so that debugging the problem is easier. The "fixed" commit
just exposed the problem.

Fixes: aea6cb99703e ("regulator: resolve supply after creating regulator")
Cc: stable@vger.kernel.org
Reported-by: Ahmad Fatoum 
Signed-off-by: Michał Mirosław 
Tested-by: Ahmad Fatoum  # stpmic1
Link: https://lore.kernel.org/r/c6171057cfc0896f950c4d8cb82df0f9f1b89ad9.1605226675.git.mirq-linux@rere.qmqm.pl
Signed-off-by: Mark Brown