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openSUSE / kdump

kernel dump helpers
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fadump/udev: Avoid fadump re-registration if kernel is hotplug ready #44

Closed sourabhjains closed 2 months ago

sourabhjains commented 4 months ago

Currently, fadump is re-registered on memory add/remove events. However, with the introduction of the kernel commit c6c5b14dac0d ("powerpc: make fadump resilient with memory add/remove events"), elfcorehdr creation is moved to the second kernel. This makes fadump re-registration on memory add/remove events unnecessary.

To indicate to userspace that the kernel is hotplug ready for the fadump case, a new sysfs entry, /sys/kernel/fadump/hotplug_ready, is introduced. If the hotplug_ready sysfs is set to 1, then there is no need to re-register fadump.

No impact for kernels without /sys/kernel/fadump/hotplug_ready sysfs node.

Relevant kernel commit links:

  1. https://msgid.link/20240422195932.1583833-2-sourabhjain@linux.ibm.com
  2. https://msgid.link/20240422195932.1583833-3-sourabhjain@linux.ibm.com
sourabhjains commented 3 months ago

Any review/comments on this PR?

sourabhjains commented 2 months ago

won't this match: TEST=="/sys/kernel/fadump/hotplug_ready" break the rule for kernels that don't have that sysfs file yet?

I tried the above test case and things were working. However, what you suggested below is a much cleaner way of handling this case. I will update the patch.

I'm not an udev expert, but I think the way to do this is prepend a new rule to the existing one like this: TEST=="/sys/kernel/fadump/hotplug_ready", PROGRAM="/bin/cat /sys/kernel/fadump/hotplug_ready", RESULT=="1", GOTO="kdump_end"

Thanks for reviewing the patch.

sourabhjains commented 2 months ago

@jiribohac I updated the patch based on your suggestion. Let me know if you have comments or suggestions on the latest change.

sourabhjains commented 2 months ago

@jiribohac Any review/comments for this PR?

Would you like me to provide some test results to push this PR forward?

jiribohac commented 2 months ago

Merged, thanks!

sourabhjains commented 2 months ago

Thanks @jiribohac for accepting the patch.