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mirror_zfs/module/spl/spl-generic.c
Brian Behlendorf d28db80fd0 Update rwlocks to track owner to ensure correct semantics 
The behavior of RW_*_HELD was updated because it was not quite right.
It is not sufficient to return non-zero when the lock is help, we must
only do this when the current task in the holder.

This means we need to track the lock owner which is not something
tracked in a Linux semaphore.  After some experimentation the
solution I settled on was to embed the Linux semaphore at the start
of a larger krwlock_t structure which includes the owner field.
This maintains good performance and allows us to cleanly intergrate
with the kernel lock analysis tools.  My reasons:

1) By placing the Linux semaphore at the start of krwlock_t we can
then simply cast krwlock_t to a rw_semaphore and pass that on to
the linux kernel.  This allows us to use '#defines so the preprocessor
can do direct replacement of the Solaris primative with the linux
equivilant.  This is important because it then maintains the location
information for each rw_* call point.

2) Additionally, by adding the owner to krwlock_t we can keep this
needed extra information adjacent to the lock itself.  This removes
the need for a fancy lookup to get the owner which is optimal for
performance.  We can also leverage the existing spin lock in the
semaphore to ensure owner is updated correctly.

3) All helper functions which do not need to strictly be implemented
as a define to preserve location information can be done as a static
inline function.

4) Adding the owner to krwlock_t allows us to remove all memory
allocations done during lock initialization.  This is good for all
the obvious reasons, we do give up the ability to specific the lock
name.  The Linux profiling tools will stringify the lock name used
in the code via the preprocessor and use that.

Update rwlocks validated on:
- SLES10   (ppc64)
- SLES11   (x86_64)
- CHAOS4.2 (x86_64)
- RHEL5.3  (x86_64)
- RHEL6    (x86_64)
- FC11     (x86_64)
2009-09-25 14:14:35 -07:00

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/*
* This file is part of the SPL: Solaris Porting Layer.
*
* Copyright (c) 2008 Lawrence Livermore National Security, LLC.
* Produced at Lawrence Livermore National Laboratory
* Written by:
* Brian Behlendorf <behlendorf1@llnl.gov>,
* Herb Wartens <wartens2@llnl.gov>,
* Jim Garlick <garlick@llnl.gov>
* UCRL-CODE-235197
*
* This is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include <sys/sysmacros.h>
#include <sys/systeminfo.h>
#include <sys/vmsystm.h>
#include <sys/vnode.h>
#include <sys/kmem.h>
#include <sys/mutex.h>
#include <sys/rwlock.h>
#include <sys/taskq.h>
#include <sys/debug.h>
#include <sys/proc.h>
#include <sys/kstat.h>
#include <sys/utsname.h>
#include <sys/file.h>
#include <linux/kmod.h>
#ifdef DEBUG_SUBSYSTEM
#undef DEBUG_SUBSYSTEM
#endif
#define DEBUG_SUBSYSTEM S_GENERIC
char spl_version[16] = "SPL v" SPL_META_VERSION;
long spl_hostid = 0;
EXPORT_SYMBOL(spl_hostid);
char hw_serial[HW_HOSTID_LEN] = "<none>";
EXPORT_SYMBOL(hw_serial);
int p0 = 0;
EXPORT_SYMBOL(p0);
#ifndef HAVE_KALLSYMS_LOOKUP_NAME
kallsyms_lookup_name_t spl_kallsyms_lookup_name_fn = SYMBOL_POISON;
#endif
int
highbit(unsigned long i)
{
register int h = 1;
ENTRY;
if (i == 0)
RETURN(0);
#if BITS_PER_LONG == 64
if (i & 0xffffffff00000000ul) {
h += 32; i >>= 32;
}
#endif
if (i & 0xffff0000) {
h += 16; i >>= 16;
}
if (i & 0xff00) {
h += 8; i >>= 8;
}
if (i & 0xf0) {
h += 4; i >>= 4;
}
if (i & 0xc) {
h += 2; i >>= 2;
}
if (i & 0x2) {
h += 1;
}
RETURN(h);
}
EXPORT_SYMBOL(highbit);
/*
* Implementation of 64 bit division for 32-bit machines.
*/
#if BITS_PER_LONG == 32
uint64_t __udivdi3(uint64_t dividend, uint64_t divisor)
{
#if defined(HAVE_DIV64_64) /* 2.6.22 - 2.6.25 API */
return div64_64(dividend, divisor);
#elif defined(HAVE_DIV64_U64) /* 2.6.26 - 2.6.x API */
return div64_u64(dividend, divisor);
#else
/* Implementation from 2.6.30 kernel */
uint32_t high, d;
high = divisor >> 32;
if (high) {
unsigned int shift = fls(high);
d = divisor >> shift;
dividend >>= shift;
} else
d = divisor;
return do_div(dividend, d);
#endif /* HAVE_DIV64_64, HAVE_DIV64_U64 */
}
EXPORT_SYMBOL(__udivdi3);
/*
* Implementation of 64 bit modulo for 32-bit machines.
*/
uint64_t __umoddi3(uint64_t dividend, uint64_t divisor)
{
return dividend - divisor * (dividend / divisor);
}
EXPORT_SYMBOL(__umoddi3);
#endif /* BITS_PER_LONG */
/* NOTE: The strtoxx behavior is solely based on my reading of the Solaris
* ddi_strtol(9F) man page. I have not verified the behavior of these
* functions against their Solaris counterparts. It is possible that I
* may have misinterpreted the man page or the man page is incorrect.
*/
int ddi_strtoul(const char *, char **, int, unsigned long *);
int ddi_strtol(const char *, char **, int, long *);
int ddi_strtoull(const char *, char **, int, unsigned long long *);
int ddi_strtoll(const char *, char **, int, long long *);
#define define_ddi_strtoux(type, valtype) \
int ddi_strtou##type(const char *str, char **endptr, \
int base, valtype *result) \
{ \
valtype last_value, value = 0; \
char *ptr = (char *)str; \
int flag = 1, digit; \
\
if (strlen(ptr) == 0) \
return EINVAL; \
\
/* Auto-detect base based on prefix */ \
if (!base) { \
if (str[0] == '0') { \
if (tolower(str[1])=='x' && isxdigit(str[2])) { \
base = 16; /* hex */ \
ptr += 2; \
} else if (str[1] >= '0' && str[1] < 8) { \
base = 8; /* octal */ \
ptr += 1; \
} else { \
return EINVAL; \
} \
} else { \
base = 10; /* decimal */ \
} \
} \
\
while (1) { \
if (isdigit(*ptr)) \
digit = *ptr - '0'; \
else if (isalpha(*ptr)) \
digit = tolower(*ptr) - 'a' + 10; \
else \
break; \
\
if (digit >= base) \
break; \
\
last_value = value; \
value = value * base + digit; \
if (last_value > value) /* Overflow */ \
return ERANGE; \
\
flag = 1; \
ptr++; \
} \
\
if (flag) \
*result = value; \
\
if (endptr) \
*endptr = (char *)(flag ? ptr : str); \
\
return 0; \
} \
#define define_ddi_strtox(type, valtype) \
int ddi_strto##type(const char *str, char **endptr, \
int base, valtype *result) \
{ \
int rc; \
\
if (*str == '-') { \
rc = ddi_strtou##type(str + 1, endptr, base, result); \
if (!rc) { \
if (*endptr == str + 1) \
*endptr = (char *)str; \
else \
*result = -*result; \
} \
} else { \
rc = ddi_strtou##type(str, endptr, base, result); \
} \
\
return rc; \
}
define_ddi_strtoux(l, unsigned long)
define_ddi_strtox(l, long)
define_ddi_strtoux(ll, unsigned long long)
define_ddi_strtox(ll, long long)
EXPORT_SYMBOL(ddi_strtoul);
EXPORT_SYMBOL(ddi_strtol);
EXPORT_SYMBOL(ddi_strtoll);
EXPORT_SYMBOL(ddi_strtoull);
int
ddi_copyin(const void *from, void *to, size_t len, int flags)
{
/* Fake ioctl() issued by kernel, 'from' is a kernel address */
if (flags & FKIOCTL) {
memcpy(to, from, len);
return 0;
}
return copyin(from, to, len);
}
EXPORT_SYMBOL(ddi_copyin);
int
ddi_copyout(const void *from, void *to, size_t len, int flags)
{
/* Fake ioctl() issued by kernel, 'from' is a kernel address */
if (flags & FKIOCTL) {
memcpy(to, from, len);
return 0;
}
return copyout(from, to, len);
}
EXPORT_SYMBOL(ddi_copyout);
#ifndef HAVE_PUT_TASK_STRUCT
/*
* This is only a stub function which should never be used. The SPL should
* never be putting away the last reference on a task structure so this will
* not be called. However, we still need to define it so the module does not
* have undefined symbol at load time. That all said if this impossible
* thing does somehow happen SBUG() immediately so we know about it.
*/
void
__put_task_struct(struct task_struct *t)
{
SBUG();
}
EXPORT_SYMBOL(__put_task_struct);
#endif /* HAVE_PUT_TASK_STRUCT */
struct new_utsname *__utsname(void)
{
#ifdef HAVE_INIT_UTSNAME
return init_utsname();
#else
return &system_utsname;
#endif
}
EXPORT_SYMBOL(__utsname);
static int
set_hostid(void)
{
char sh_path[] = "/bin/sh";
char *argv[] = { sh_path,
"-c",
"/usr/bin/hostid >/proc/sys/kernel/spl/hostid",
NULL };
char *envp[] = { "HOME=/",
"TERM=linux",
"PATH=/sbin:/usr/sbin:/bin:/usr/bin",
NULL };
int rc;
/* Doing address resolution in the kernel is tricky and just
* not a good idea in general. So to set the proper 'hw_serial'
* use the usermodehelper support to ask '/bin/sh' to run
* '/usr/bin/hostid' and redirect the result to /proc/sys/spl/hostid
* for us to use. It's a horrific solution but it will do for now.
*/
rc = call_usermodehelper(sh_path, argv, envp, 1);
if (rc)
printk("SPL: Failed user helper '%s %s %s', rc = %d\n",
argv[0], argv[1], argv[2], rc);
return rc;
}
uint32_t
zone_get_hostid(void *zone)
{
unsigned long hostid;
/* Only the global zone is supported */
ASSERT(zone == NULL);
if (ddi_strtoul(hw_serial, NULL, HW_HOSTID_LEN-1, &hostid) != 0)
return HW_INVALID_HOSTID;
return (uint32_t)hostid;
}
EXPORT_SYMBOL(zone_get_hostid);
#ifndef HAVE_KALLSYMS_LOOKUP_NAME
/*
* Because kallsyms_lookup_name() is no longer exported in the
* mainline kernel we are forced to resort to somewhat drastic
* measures. This function replaces the functionality by performing
* an upcall to user space where /proc/kallsyms is consulted for
* the requested address.
*/
#define GET_KALLSYMS_ADDR_CMD \
"awk '{ if ( $3 == \"kallsyms_lookup_name\") { print $1 } }' " \
"/proc/kallsyms >/proc/sys/kernel/spl/kallsyms_lookup_name"
static int
set_kallsyms_lookup_name(void)
{
char sh_path[] = "/bin/sh";
char *argv[] = { sh_path,
"-c",
GET_KALLSYMS_ADDR_CMD,
NULL };
char *envp[] = { "HOME=/",
"TERM=linux",
"PATH=/sbin:/usr/sbin:/bin:/usr/bin",
NULL };
int rc;
rc = call_usermodehelper(sh_path, argv, envp, 1);
if (rc)
printk("SPL: Failed user helper '%s %s %s', rc = %d\n",
argv[0], argv[1], argv[2], rc);
return rc;
}
#endif
static int __init spl_init(void)
{
int rc = 0;
if ((rc = debug_init()))
return rc;
if ((rc = spl_kmem_init()))
GOTO(out1, rc);
if ((rc = spl_mutex_init()))
GOTO(out2, rc);
if ((rc = spl_rw_init()))
GOTO(out3, rc);
if ((rc = spl_taskq_init()))
GOTO(out4, rc);
if ((rc = vn_init()))
GOTO(out5, rc);
if ((rc = proc_init()))
GOTO(out6, rc);
if ((rc = kstat_init()))
GOTO(out7, rc);
if ((rc = set_hostid()))
GOTO(out8, rc = -EADDRNOTAVAIL);
#ifndef HAVE_KALLSYMS_LOOKUP_NAME
if ((rc = set_kallsyms_lookup_name()))
GOTO(out8, rc = -EADDRNOTAVAIL);
#endif /* HAVE_KALLSYMS_LOOKUP_NAME */
if ((rc = spl_kmem_init_kallsyms_lookup()))
GOTO(out8, rc);
printk("SPL: Loaded Solaris Porting Layer v%s\n", SPL_META_VERSION);
RETURN(rc);
out8:
kstat_fini();
out7:
proc_fini();
out6:
vn_fini();
out5:
spl_taskq_fini();
out4:
spl_rw_fini();
out3:
spl_mutex_fini();
out2:
spl_kmem_fini();
out1:
debug_fini();
printk("SPL: Failed to Load Solaris Porting Layer v%s, "
"rc = %d\n", SPL_META_VERSION, rc);
return rc;
}
static void spl_fini(void)
{
ENTRY;
printk("SPL: Unloaded Solaris Porting Layer v%s\n", SPL_META_VERSION);
kstat_fini();
proc_fini();
vn_fini();
spl_taskq_fini();
spl_rw_fini();
spl_mutex_fini();
spl_kmem_fini();
debug_fini();
}
module_init(spl_init);
module_exit(spl_fini);
MODULE_AUTHOR("Lawrence Livermore National Labs");
MODULE_DESCRIPTION("Solaris Porting Layer");
MODULE_LICENSE("GPL");
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