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pwm: Two fixes and a maintainer update

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Included here are three changes:
 
  - pwm: Ensure ioctl() returns a negative errno on error
    This affects two ioctls on /dev/pwmchipX where the return value of
    copy_to_user() was passed to userspace. This is fixed to return
    -EFAULT now instead.
    You might argue that this is an ABI change, but I still think it's
    sensible to be fixed because a) other exit paths already return
    -EFAULT so userspace must be aware of this return value; b) the
    interface is somewhat new (commit v6.17-rc1~181^2~35 ("pwm: Add
    support for pwmchip devices for faster and easier userspace access"))
    and the only known user is libpwm which relies on the fixed
    semantics (and uses the ioctl correctly and thus doesn't trigger that
    problematic error path); and c) it's very unlikely that
    copy_to_user() fails if a moment before copy_from_user() on the same
    memory chunk succeeded.
 
  - pwm: max7360: Populate missing .sizeof_wfhw in max7360_pwm_ops
    This fixes an oversight in commit v6.18-rc1~168^2~3^2~6 which added
    support for the max7360 driver. There is no user-visible effect
    because the .sizeof_wfhw member is just a safe guard that the memory
    provided by the core is big enough. While it currently is big enough
    and there is no reason to assume that will change, doing that
    correctly is necessary.
 
  - MAINTAINERS: Add myself as reviewer for PWM rust drivers
    "Myself" here is Michal Wilczynski who cares for the Rust parts of
    the pwm subsystem. Several of the patches sent recently for the (for
    now) only Rust pwm driver did not add Michal to Cc which resulted in
    the patches waiting for review as I thought Michal would care but he
    wasn't aware of them.
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Merge tag 'pwm/for-6.19-rc7-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/ukleinek/linux

Pull pwm fixes and a maintainer update from Uwe Kleine-König:

 - pwm: Ensure ioctl() returns a negative errno on error

   This affects two ioctls on /dev/pwmchipX where the return value of
   copy_to_user() was passed to userspace. This is fixed to return
   -EFAULT now instead.

 - pwm: max7360: Populate missing .sizeof_wfhw in max7360_pwm_ops

   This fixes an oversight in the original commit that added support for
   the max7360 driver (d93a75d94b: "pwm: max7360: Add MAX7360 PWM
   support"). There is no user-visible effect because the .sizeof_wfhw
   member is just a safe guard that the memory provided by the core is
   big enough. While it currently is big enough and there is no reason
   to assume that will change, doing that correctly is necessary.

 - MAINTAINERS: Add Michal Wilczynski as reviewer for PWM rust drivers

   Michal cares for the Rust parts of the pwm subsystem. Several of the
   patches sent recently for the (for now) only Rust pwm driver did not
   add Michal to Cc which resulted in the patches waiting for review as
   I thought Michal would care but he wasn't aware of them.

* tag 'pwm/for-6.19-rc7-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/ukleinek/linux:
  MAINTAINERS: Add myself as reviewer for PWM rust drivers
  pwm: max7360: Populate missing .sizeof_wfhw in max7360_pwm_ops
  pwm: Ensure ioctl() returns a negative errno on error
This commit is contained in:
Linus Torvalds 2026-01-20 09:46:29 -08:00
commit 8f7537efbe
3 changed files with 11 additions and 4 deletions
Download patch file Download diff file Expand all files Collapse all files

4
MAINTAINERS
View file

@ -21103,6 +21103,10 @@ S: Maintained
F: rust/helpers/pwm.c
F: rust/kernel/pwm.rs
PWM SUBSYSTEM DRIVERS [RUST]
R: Michal Wilczynski <m.wilczynski@samsung.com>
F: drivers/pwm/*.rs
PXA GPIO DRIVER
M: Robert Jarzmik <robert.jarzmik@free.fr>
L: linux-gpio@vger.kernel.org

10
drivers/pwm/core.c
View file

@ -2295,8 +2295,9 @@ static long pwm_cdev_ioctl(struct file *file, unsigned int cmd, unsigned long ar
.duty_offset_ns = wf.duty_offset_ns,
};
return copy_to_user((struct pwmchip_waveform __user *)arg,
&cwf, sizeof(cwf));
ret = copy_to_user((struct pwmchip_waveform __user *)arg,
&cwf, sizeof(cwf));
return ret ? -EFAULT : 0;
}
case PWM_IOCTL_GETWF:
@ -2329,8 +2330,9 @@ static long pwm_cdev_ioctl(struct file *file, unsigned int cmd, unsigned long ar
.duty_offset_ns = wf.duty_offset_ns,
};
return copy_to_user((struct pwmchip_waveform __user *)arg,
&cwf, sizeof(cwf));
ret = copy_to_user((struct pwmchip_waveform __user *)arg,
&cwf, sizeof(cwf));
return ret ? -EFAULT : 0;
}
case PWM_IOCTL_SETROUNDEDWF:

1
drivers/pwm/pwm-max7360.c
View file

@ -153,6 +153,7 @@ static int max7360_pwm_read_waveform(struct pwm_chip *chip,
}
static const struct pwm_ops max7360_pwm_ops = {
.sizeof_wfhw = sizeof(struct max7360_pwm_waveform),
.request = max7360_pwm_request,
.round_waveform_tohw = max7360_pwm_round_waveform_tohw,
.round_waveform_fromhw = max7360_pwm_round_waveform_fromhw,