Hi George,

On 05.03.25 11:10, George Cherian wrote:

This series adds a new kernel command line option to watchdog core to
stop the watchdog on panic. This is useul in certain systems which prevents
successful loading of kdump kernel due to watchdog reset.

Some of the watchdog drivers stop function could sleep. For such
drivers the stop_on_panic is not valid as the notifier callback happens
in atomic context. Introduce WDIOF_STOP_MAYSLEEP flag to watchdog_info
options to indicate whether the stop function would sleep.

Did you consider having a reset_on_panic instead, which sets a user-specified
timeout on panic? This would make the mechanism useful also for watchdogs
that can't be disabled and would protect against system lock up:
Consider a memory-corruption bug (perhaps externally via DMA), which partially
overwrites both main and kdump kernel. With a disabled watchdog, the system
may not be able to recover on its own.

If you did consider it, what made you decide against it?

Thanks,
Ahmad

Changelog:
v1 -> v2
- Remove the per driver flag setting option
- Take the parameter via kernel command-line parameter to watchdog_core.

v2 -> v3
- Remove the helper function watchdog_stop_on_panic() from watchdog.h.
- There are no users for this. 

v3 -> v4
- Since the panic notifier is in atomic context, watchdog functions
  which sleep can't be called. 
- Add an options flag WDIOF_STOP_MAYSLEEP to indicate whether stop
  function sleeps.
- Simplify the stop_on_panic kernel command line parsing.
- Enable the panic notiffier only if the watchdog stop function doesn't
  sleep

George Cherian (2):
  watchdog: Add a new flag WDIOF_STOP_MAYSLEEP
  drivers: watchdog: Add support for panic notifier callback

 drivers/watchdog/advantech_ec_wdt.c |  3 ++-
 drivers/watchdog/arm_smc_wdt.c      |  3 ++-
 drivers/watchdog/armada_37xx_wdt.c  |  2 +-
 drivers/watchdog/asm9260_wdt.c      |  2 +-
 drivers/watchdog/bcm47xx_wdt.c      |  3 ++-
 drivers/watchdog/bd9576_wdt.c       |  2 +-
 drivers/watchdog/bd96801_wdt.c      |  2 +-
 drivers/watchdog/cgbc_wdt.c         |  2 +-
 drivers/watchdog/cros_ec_wdt.c      |  5 ++++-
 drivers/watchdog/da9052_wdt.c       |  3 ++-
 drivers/watchdog/da9055_wdt.c       |  4 +++-
 drivers/watchdog/da9062_wdt.c       |  4 +++-
 drivers/watchdog/da9063_wdt.c       |  4 +++-
 drivers/watchdog/db8500_wdt.c       |  5 ++++-
 drivers/watchdog/dw_wdt.c           |  5 +++--
 drivers/watchdog/f71808e_wdt.c      |  3 ++-
 drivers/watchdog/gpio_wdt.c         |  2 +-
 drivers/watchdog/i6300esb.c         |  5 ++++-
 drivers/watchdog/imx_sc_wdt.c       |  2 +-
 drivers/watchdog/intel-mid_wdt.c    |  5 ++++-
 drivers/watchdog/it87_wdt.c         |  5 ++++-
 drivers/watchdog/jz4740_wdt.c       |  5 ++++-
 drivers/watchdog/kempld_wdt.c       |  3 ++-
 drivers/watchdog/lenovo_se10_wdt.c  |  5 ++++-
 drivers/watchdog/max77620_wdt.c     |  5 ++++-
 drivers/watchdog/mei_wdt.c          |  3 ++-
 drivers/watchdog/menf21bmc_wdt.c    |  4 +++-
 drivers/watchdog/mlx_wdt.c          |  2 +-
 drivers/watchdog/msc313e_wdt.c      |  5 ++++-
 drivers/watchdog/npcm_wdt.c         |  3 ++-
 drivers/watchdog/omap_wdt.c         |  5 ++++-
 drivers/watchdog/pm8916_wdt.c       |  5 +++--
 drivers/watchdog/pseries-wdt.c      |  2 +-
 drivers/watchdog/rave-sp-wdt.c      |  5 ++++-
 drivers/watchdog/renesas_wdt.c      |  7 ++++--
 drivers/watchdog/retu_wdt.c         |  5 ++++-
 drivers/watchdog/rn5t618_wdt.c      |  6 +++--
 drivers/watchdog/rzg2l_wdt.c        |  5 ++++-
 drivers/watchdog/rzv2h_wdt.c        |  5 ++++-
 drivers/watchdog/shwdt.c            |  6 +++--
 drivers/watchdog/sl28cpld_wdt.c     |  5 ++++-
 drivers/watchdog/softdog.c          |  5 ++++-
 drivers/watchdog/sp805_wdt.c        |  5 ++++-
 drivers/watchdog/starfive-wdt.c     |  3 ++-
 drivers/watchdog/stpmic1_wdt.c      |  5 ++++-
 drivers/watchdog/ts4800_wdt.c       |  5 ++++-
 drivers/watchdog/twl4030_wdt.c      |  5 ++++-
 drivers/watchdog/uniphier_wdt.c     |  3 ++-
 drivers/watchdog/w83627hf_wdt.c     |  5 ++++-
 drivers/watchdog/watchdog_core.c    | 35 +++++++++++++++++++++++++++++
 drivers/watchdog/wm831x_wdt.c       |  5 ++++-
 drivers/watchdog/wm8350_wdt.c       |  5 ++++-
 drivers/watchdog/xen_wdt.c          |  5 ++++-
 drivers/watchdog/ziirave_wdt.c      |  5 ++++-
 include/linux/watchdog.h            |  2 ++
 include/uapi/linux/watchdog.h       |  1 +
 56 files changed, 198 insertions(+), 58 deletions(-)

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