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Fix spl_kmem_init_kallsyms_lookup() panic

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Due to I/O buffering the helper may return successfully before
the proc handler has a chance to execute.  To catch this case
wait up to 1 second to verify spl_kallsyms_lookup_name_fn was
updated to a non SYMBOL_POISON value.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes zfsonlinux/zfs#699
Closes zfsonlinux/zfs#859
This commit is contained in:
Brian Behlendorf 2012-12-18 17:02:27 -08:00
parent 30196bfd42
commit 034f1b331e
3 changed files with 22 additions and 0 deletions
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1
include/linux/kallsyms_compat.h
View File

@ -34,6 +34,7 @@
#else
extern wait_queue_head_t spl_kallsyms_lookup_name_waitq;
typedef unsigned long (*kallsyms_lookup_name_t)(const char *);
extern kallsyms_lookup_name_t spl_kallsyms_lookup_name_fn;
#define spl_kallsyms_lookup_name(name) spl_kallsyms_lookup_name_fn(name)

19
module/spl/spl-generic.c
View File

@ -64,6 +64,7 @@ proc_t p0 = { 0 };
EXPORT_SYMBOL(p0);
#ifndef HAVE_KALLSYMS_LOOKUP_NAME
DECLARE_WAIT_QUEUE_HEAD(spl_kallsyms_lookup_name_waitq);
kallsyms_lookup_name_t spl_kallsyms_lookup_name_fn = SYMBOL_POISON;
#endif
@ -607,6 +608,24 @@ set_kallsyms_lookup_name(void)
int rc;
rc = call_usermodehelper(argv[0], argv, envp, 1);
/*
* Due to I/O buffering the helper may return successfully before
* the proc handler has a chance to execute. To catch this case
* wait up to 1 second to verify spl_kallsyms_lookup_name_fn was
* updated to a non SYMBOL_POISON value.
*/
if (rc == 0) {
rc = wait_event_timeout(spl_kallsyms_lookup_name_waitq,
spl_kallsyms_lookup_name_fn != SYMBOL_POISON, HZ);
if (rc == 0)
rc = -ETIMEDOUT;
else if (spl_kallsyms_lookup_name_fn == SYMBOL_POISON)
rc = -EFAULT;
else
rc = 0;
}
if (rc)
printk("SPL: Failed user helper '%s %s %s', rc = %d\n",
argv[0], argv[1], argv[2], rc);

2
module/spl/spl-proc.c
View File

@ -546,6 +546,8 @@ SPL_PROC_HANDLER(proc_dokallsyms_lookup_name)
spl_kallsyms_lookup_name_fn =
(kallsyms_lookup_name_t)simple_strtoul(str, &end, 16);
wake_up(&spl_kallsyms_lookup_name_waitq);
if (str == end)
SRETURN(-EINVAL);