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pstore: Convert buf_lock to semaphore

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Instead of running with interrupts disabled, use a semaphore. This should
make it easier for backends that may need to sleep (e.g. EFI) when
performing a write:

|BUG: sleeping function called from invalid context at kernel/sched/completion.c:99
|in_atomic(): 1, irqs_disabled(): 1, pid: 2236, name: sig-xstate-bum
|Preemption disabled at:
|[<ffffffff99d60512>] pstore_dump+0x72/0x330
|CPU: 26 PID: 2236 Comm: sig-xstate-bum Tainted: G      D           4.20.0-rc3 #45
|Call Trace:
| dump_stack+0x4f/0x6a
| ___might_sleep.cold.91+0xd3/0xe4
| __might_sleep+0x50/0x90
| wait_for_completion+0x32/0x130
| virt_efi_query_variable_info+0x14e/0x160
| efi_query_variable_store+0x51/0x1a0
| efivar_entry_set_safe+0xa3/0x1b0
| efi_pstore_write+0x109/0x140
| pstore_dump+0x11c/0x330
| kmsg_dump+0xa4/0xd0
| oops_exit+0x22/0x30
...

Reported-by: Sebastian Andrzej Siewior <[email protected]>
Fixes: 21b3ddd39f ("efi: Don't use spinlocks for efi vars")
Signed-off-by: Kees Cook <[email protected]>
This commit is contained in:
Kees Cook 2018-11-30 14:36:58 -08:00
commit ea84b580b9
6 changed files with 27 additions and 32 deletions
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4
drivers/firmware/efi/efi-pstore.c
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@ -259,8 +259,7 @@ static int efi_pstore_write(struct pstore_record *record)
efi_name[i] = name[i];
ret = efivar_entry_set_safe(efi_name, vendor, PSTORE_EFI_ATTRIBUTES,
!pstore_cannot_block_path(record->reason),
record->size, record->psi->buf);
preemptible(), record->size, record->psi->buf);
if (record->reason == KMSG_DUMP_OOPS)
efivar_run_worker();
@ -369,7 +368,6 @@ static __init int efivars_pstore_init(void)
return -ENOMEM;
efi_pstore_info.bufsize = 1024;
spin_lock_init(&efi_pstore_info.buf_lock);
if (pstore_register(&efi_pstore_info)) {
kfree(efi_pstore_info.buf);