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Going more deep into this: 

This is the initial pcim_intx_resoure associated resource being added during first (CCP) driver load:

[   40.418933]  pcim_intx+0x3a/0x120
[   40.418936]  pci_intx+0x8b/0xa0
[   40.418939]  __pci_enable_msix_range+0x369/0x530
[   40.418943]  pci_enable_msix_range+0x18/0x20
[   40.418946]  sp_pci_probe+0x106/0x310 [ccp]
[   40.418965] ipmi device interface
[   40.418960]  ? srso_alias_return_thunk+0x5/0xfbef5
[   40.418969]  local_pci_probe+0x4f/0xb0
[   40.418973]  work_for_cpu_fn+0x1e/0x30
[   40.418976]  process_one_work+0x183/0x350
[   40.418980]  worker_thread+0x2df/0x3f0
[   40.418982]  ? __pfx_worker_thread+0x10/0x10
[   40.418985]  kthread+0xd0/0x100
[   40.418987]  ? __pfx_kthread+0x10/0x10
[   40.418990]  ret_from_fork+0x40/0x60
[   40.418993]  ? __pfx_kthread+0x10/0x10
[   40.418996]  ret_from_fork_asm+0x1a/0x30
[   40.419001]  </TASK>
..
..
[   40.419012] ccp 0000:23:00.1: DEVRES ADD 00000000fbd19618 0xffff8cfaa528d140 pcim_intx_restore (4 bytes)

Now, at driver unload: 
devres_release_all() -> remove_nodes() -> release_nodes() ...

remove_nodes() moves normal devres entries to the todo list, as can be seen with the following log:
...
[  218.245241] moving node 00000000fbd19618 0xffff8cfaa528d140 from devres to todo list
...

So, now this pcim_intx_resource associated resource is no longer part of dev->devres_head list and has been
moved to the todo list.

Later, when release_nodes() is invoked, it calls the associated release() callback associated with this devres:
...
[  218.331000] ccp 0000:23:00.1: DEVRES REL 00000000fbd19618 0xffff8cfaa528d140 pcim_intx_restore (4 bytes)
...

The call flow for that is:
pcim_intx_restore() -> pci_intx() -> pcim_intx() ...

Now, pcim_intx() calls get_or_create_intx_devres() which tries to find it's associated devres using devres_find(), but 
that fails to find the devres, as the devres is no longer on dev->devres_head and has been moved to todo list.

Therefore, get_or_create_intx_devres() adds a new devres at driver unload/detach time:
...
[  218.361330] ccp 0000:23:00.1: DEVRES ADD 0000000057f8e767 0xffff8cfa867b7740 pcim_intx_restore (4 bytes)
...

But, then this is an issue as pcim_intx() is supposed to restore the original PCI INTx state on driver detach, but it now
operating on a newly added devres and not the original devres (added at driver probe) which contains the original PCI INTx
state, so it will be restoring an incorrect PCI INTx state ?

Additionally, this newly added devres causes driver reload/probe failure as really_probe() now finds resources present
before probing.

Not sure, if this issue has been observed with other PCI device drivers.

Thanks,
Ashish



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