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pstore: Return unique error if backend registration excluded by kerne…
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…l param

This is patch 1/3 of a patch set that avoids what misleadingly appears
to be a error during boot:

ERST: Could not register with persistent store

This message is displayed if the system has a valid ACPI ERST table and the
pstore.backend kernel parameter has been used to disable use of ERST by
pstore. But this same message is used for errors that preclude registration.

As part of fixing this, return a unique error status from pstore_register
if the pstore.backend kernel parameter selects a specific facility other
than the requesting facility and check for this condition before any others.
This allows the caller to distinquish this benign case from the other failure
cases.

Also, print an informational console message about which facility
successfully registered as the pstore backend. Since there are various
kernel parameters, config build options, and boot-time errors that can
influence which facility registers with pstore, it's useful to have a
positive indication.

Signed-off-by: Lenny Szubowicz <[email protected]>
Reported-by: Naotaka Hamaguchi <[email protected]>
Signed-off-by: Tony Luck <[email protected]>
LennySzubowicz authored and aegl committed Jun 28, 2013
1 parent bf28833 commit 8e48b1a
Showing 1 changed file with 6 additions and 5 deletions.
11 changes: 6 additions & 5 deletions fs/pstore/platform.c
Original file line number Diff line number Diff line change
@@ -239,17 +239,15 @@ int pstore_register(struct pstore_info *psi)
{
struct module *owner = psi->owner;

if (backend && strcmp(backend, psi->name))
return -EPERM;

spin_lock(&pstore_lock);
if (psinfo) {
spin_unlock(&pstore_lock);
return -EBUSY;
}

if (backend && strcmp(backend, psi->name)) {
spin_unlock(&pstore_lock);
return -EINVAL;
}

if (!psi->write)
psi->write = pstore_write_compat;
psinfo = psi;
@@ -274,6 +272,9 @@ int pstore_register(struct pstore_info *psi)
add_timer(&pstore_timer);
}

pr_info("pstore: Registered %s as persistent store backend\n",
psi->name);

return 0;
}
EXPORT_SYMBOL_GPL(pstore_register);

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