[PATCH] s390: cpu hotplug bugs.

From: Martin Schwidefsky
Date: Fri Jul 09 2004 - 12:20:52 EST

[PATCH] s390: cpu hotplug bugs.

From: Ursula Braun-Krahl <braunu@xxxxxxxxxx>
From: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>

iucv driver changes:
- Fix iucv declare/retrieve buffer which the cpu hotplug patch has broken.
- Make smp_call_function_on call func(info) in non-smp kernels.
- Use a spinlock to get smp_get_cpu/smp_put_cpu race free.

Signed-off-by: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>

diffstat:
arch/s390/kernel/smp.c | 38 ++++++++++++++-----------
drivers/s390/net/iucv.c | 71 +++++++++++++++++++++++-------------------------
include/asm-s390/smp.h | 8 ++++-
3 files changed, 64 insertions(+), 53 deletions(-)

diff -urN linux-2.6/arch/s390/kernel/smp.c linux-2.6-s390/arch/s390/kernel/smp.c
--- linux-2.6/arch/s390/kernel/smp.c Fri Jul 9 18:58:41 2004
+++ linux-2.6-s390/arch/s390/kernel/smp.c Fri Jul 9 18:58:54 2004
@@ -582,38 +582,45 @@

/* Reserving and releasing of CPUs */

-static atomic_t smp_cpu_reserved[NR_CPUS];
+static spinlock_t smp_reserve_lock = SPIN_LOCK_UNLOCKED;
+static int smp_cpu_reserved[NR_CPUS];

int
smp_get_cpu(cpumask_t cpu_mask)
{
- int val, cpu;
+ unsigned long flags;
+ int cpu;

+ spin_lock_irqsave(&smp_reserve_lock, flags);
/* Try to find an already reserved cpu. */
for_each_cpu_mask(cpu, cpu_mask) {
- while ((val = atomic_read(&smp_cpu_reserved[cpu])) != 0) {
- if (!atomic_compare_and_swap(val, val + 1,
- &smp_cpu_reserved[cpu]))
- /* Found one. */
- goto out;
+ if (smp_cpu_reserved[cpu] != 0) {
+ smp_cpu_reserved[cpu]++;
+ /* Found one. */
+ goto out;
}
}
/* Reserve a new cpu from cpu_mask. */
for_each_cpu_mask(cpu, cpu_mask) {
- atomic_inc(&smp_cpu_reserved[cpu]);
- if (cpu_online(cpu))
+ if (cpu_online(cpu)) {
+ smp_cpu_reserved[cpu]++;
goto out;
- atomic_dec(&smp_cpu_reserved[cpu]);
+ }
}
cpu = -ENODEV;
out:
+ spin_unlock_irqrestore(&smp_reserve_lock, flags);
return cpu;
}

void
smp_put_cpu(int cpu)
{
- atomic_dec(&smp_cpu_reserved[cpu]);
+ unsigned long flags;
+
+ spin_lock_irqsave(&smp_reserve_lock, flags);
+ smp_cpu_reserved[cpu]--;
+ spin_unlock_irqrestore(&smp_reserve_lock, flags);
}

static inline int
@@ -682,10 +689,9 @@
unsigned long flags;
ec_creg_mask_parms cr_parms;

- local_irq_save(flags);
-
- if (atomic_read(&smp_cpu_reserved[smp_processor_id()])) {
- local_irq_restore(flags);
+ spin_lock_irqsave(&smp_reserve_lock, flags);
+ if (smp_cpu_reserved[smp_processor_id()] != 0) {
+ spin_unlock_irqrestore(&smp_reserve_lock, flags);
return -EBUSY;
}

@@ -715,7 +721,7 @@
cr_parms.andvals[14] = ~(1<<28 | 1<<27 | 1<<26 | 1<<25 | 1<<24);
smp_ctl_bit_callback(&cr_parms);

- local_irq_restore(flags);
+ spin_unlock_irqrestore(&smp_reserve_lock, flags);
return 0;
}

diff -urN linux-2.6/drivers/s390/net/iucv.c linux-2.6-s390/drivers/s390/net/iucv.c
--- linux-2.6/drivers/s390/net/iucv.c Fri Jul 9 18:58:43 2004
+++ linux-2.6-s390/drivers/s390/net/iucv.c Fri Jul 9 18:58:54 2004
@@ -1,5 +1,5 @@
/*
- * $Id: iucv.c,v 1.34 2004/06/24 10:53:48 braunu Exp $
+ * $Id: iucv.c,v 1.38 2004/07/09 15:59:53 mschwide Exp $
*
* IUCV network driver
*
@@ -29,7 +29,7 @@
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*
- * RELEASE-TAG: IUCV lowlevel driver $Revision: 1.34 $
+ * RELEASE-TAG: IUCV lowlevel driver $Revision: 1.38 $
*
*/

@@ -354,7 +354,7 @@
static void
iucv_banner(void)
{
- char vbuf[] = "$Revision: 1.34 $";
+ char vbuf[] = "$Revision: 1.38 $";
char *version = vbuf;

if ((version = strchr(version, ':'))) {
@@ -386,7 +386,7 @@
}

ret = bus_register(&iucv_bus);
- if (ret != 0) {
+ if (ret) {
printk(KERN_ERR "IUCV: failed to register bus.\n");
return ret;
}
@@ -527,7 +527,7 @@
*/
list_for_each(lh, &iucv_handler_table) {
handler *h = list_entry(lh, handler, list);
- if (memcmp(&new->id, &h->id, sizeof(h->id)) == 0) {
+ if (!memcmp(&new->id, &h->id, sizeof(h->id))) {
iucv_debug(1, "ret 1");
spin_unlock_irqrestore (&iucv_lock, flags);
return 1;
@@ -642,8 +642,6 @@
{
iparml_db *parm;

- if (smp_processor_id() != iucv_cpuid)
- return;
parm = (iparml_db *)grab_param();
parm->ipbfadr1 = virt_to_phys(iucv_external_int_buffer);
if ((*((ulong *)result) = b2f0(DECLARE_BUFFER, parm)) == 1)
@@ -662,8 +660,6 @@
{
iparml_control *parm;

- if (smp_processor_id() != iucv_cpuid)
- return;
parm = (iparml_control *)grab_param();
b2f0(RETRIEVE_BUFFER, parm);
release_param(parm);
@@ -683,13 +679,18 @@
ulong b2f0_result;

iucv_debug(1, "entering");
+ b2f0_result = -ENODEV;
spin_lock_irqsave (&iucv_lock, flags);
if (iucv_cpuid == -1) {
/* Reserve any cpu for use by iucv. */
iucv_cpuid = smp_get_cpu(CPU_MASK_ALL);
spin_unlock_irqrestore (&iucv_lock, flags);
- smp_call_function(iucv_declare_buffer_cpuid,
- &b2f0_result, 0, 1);
+ smp_call_function_on(iucv_declare_buffer_cpuid,
+ &b2f0_result, 0, 1, iucv_cpuid);
+ if (b2f0_result) {
+ smp_put_cpu(iucv_cpuid);
+ iucv_cpuid = -1;
+ }
iucv_debug(1, "Address of EIB = %p", iucv_external_int_buffer);
} else {
spin_unlock_irqrestore (&iucv_lock, flags);
@@ -710,7 +711,8 @@
{
iucv_debug(1, "entering");
if (iucv_cpuid != -1) {
- smp_call_function(iucv_retrieve_buffer_cpuid, 0, 0, 1);
+ smp_call_function_on(iucv_retrieve_buffer_cpuid,
+ 0, 0, 1, iucv_cpuid);
/* Release the cpu reserved by iucv_declare_buffer. */
smp_put_cpu(iucv_cpuid);
iucv_cpuid = -1;
@@ -872,6 +874,9 @@
iucv_remove_handler(new_handler);
kfree(new_handler);
switch(rc) {
+ case -ENODEV:
+ err = "No CPU can be reserved";
+ break;
case 0x03:
err = "Directory error";
break;
@@ -892,7 +897,7 @@
"returned error 0x%02lx (%s)\n", __FUNCTION__, rc, err);
return NULL;
}
- if (register_flag == 0) {
+ if (!register_flag) {
/* request the 0x4000 external interrupt */
rc = register_external_interrupt (0x4000, iucv_irq_handler);
if (rc) {
@@ -1042,7 +1047,7 @@
parm->ipflags1 = (__u8)flags1;
b2f0_result = b2f0(ACCEPT, parm);

- if (b2f0_result == 0) {
+ if (!b2f0_result) {
if (msglim)
*msglim = parm->ipmsglim;
if (pgm_data)
@@ -1182,7 +1187,7 @@
memcpy(&local_parm, parm, sizeof(local_parm));
release_param(parm);
parm = &local_parm;
- if (b2f0_result == 0)
+ if (!b2f0_result)
add_pathid_result = __iucv_add_pathid(parm->ippathid, h);
spin_unlock_irqrestore (&iucv_lock, flags);

@@ -1242,7 +1247,7 @@
parm->ipflags1 |= (IPSRCCLS | IPFGMID | IPFGPID);
b2f0_result = b2f0(PURGE, parm);

- if ((b2f0_result == 0) && audit) {
+ if (!b2f0_result && audit) {
memcpy(audit, parm->ipaudit, sizeof(parm->ipaudit));
/* parm->ipaudit has only 3 bytes */
*audit >>= 8;
@@ -1406,7 +1411,7 @@

b2f0_result = b2f0(RECEIVE, parm);

- if (b2f0_result == 0 || b2f0_result == 5) {
+ if (!b2f0_result || b2f0_result == 5) {
if (flags1_out) {
iucv_debug(2, "*flags1_out = %d", *flags1_out);
*flags1_out = (parm->ipflags1 & (~0x07));
@@ -1496,7 +1501,7 @@

b2f0_result = b2f0(RECEIVE, parm);

- if (b2f0_result == 0 || b2f0_result == 5) {
+ if (!b2f0_result || b2f0_result == 5) {

if (flags1_out) {
iucv_debug(2, "*flags1_out = %d", *flags1_out);
@@ -1543,7 +1548,7 @@
*residual_length = abs (buflen - 8);

if (residual_buffer) {
- if (moved == 0)
+ if (!moved)
*residual_buffer = (ulong) buffer;
else
*residual_buffer =
@@ -1645,7 +1650,7 @@

b2f0_result = b2f0(REPLY, parm);

- if ((b2f0_result == 0) || (b2f0_result == 5)) {
+ if ((!b2f0_result) || (b2f0_result == 5)) {
if (ipbfadr2)
*ipbfadr2 = parm->ipbfadr2;
if (ipbfln2f)
@@ -1711,7 +1716,7 @@

b2f0_result = b2f0(REPLY, parm);

- if ((b2f0_result == 0) || (b2f0_result == 5)) {
+ if ((!b2f0_result) || (b2f0_result == 5)) {

if (ipbfadr2)
*ipbfadr2 = parm->ipbfadr2;
@@ -1837,7 +1842,7 @@

b2f0_result = b2f0(SEND, parm);

- if ((b2f0_result == 0) && (msgid))
+ if ((!b2f0_result) && (msgid))
*msgid = parm->ipmsgid;
release_param(parm);

@@ -1891,7 +1896,7 @@
parm->ipflags1 = (IPNORPY | IPBUFLST | flags1);
b2f0_result = b2f0(SEND, parm);

- if ((b2f0_result == 0) && (msgid))
+ if ((!b2f0_result) && (msgid))
*msgid = parm->ipmsgid;
release_param(parm);

@@ -1937,7 +1942,7 @@

b2f0_result = b2f0(SEND, parm);

- if ((b2f0_result == 0) && (msgid))
+ if ((!b2f0_result) && (msgid))
*msgid = parm->ipmsgid;
release_param(parm);

@@ -1998,7 +2003,7 @@

b2f0_result = b2f0(SEND, parm);

- if ((b2f0_result == 0) && (msgid))
+ if ((!b2f0_result) && (msgid))
*msgid = parm->ipmsgid;
release_param(parm);

@@ -2059,7 +2064,7 @@
parm->ipmsgtag = msgtag;
parm->ipflags1 = (IPBUFLST | IPANSLST | flags1);
b2f0_result = b2f0(SEND, parm);
- if ((b2f0_result == 0) && (msgid))
+ if ((!b2f0_result) && (msgid))
*msgid = parm->ipmsgid;
release_param(parm);

@@ -2117,7 +2122,7 @@

b2f0_result = b2f0(SEND, parm);

- if ((b2f0_result == 0) && (msgid))
+ if ((!b2f0_result) && (msgid))
*msgid = parm->ipmsgid;
release_param(parm);

@@ -2178,7 +2183,7 @@
parm->ipflags1 = (IPRMDATA | IPANSLST | flags1);
memcpy(parm->iprmmsg, prmmsg, sizeof(parm->iprmmsg));
b2f0_result = b2f0(SEND, parm);
- if ((b2f0_result == 0) && (msgid))
+ if ((!b2f0_result) && (msgid))
*msgid = parm->ipmsgid;
release_param(parm);

@@ -2191,9 +2196,6 @@
{
iparml_set_mask *parm;

- if (smp_processor_id() != iucv_cpuid)
- return;
-
iucv_debug(1, "entering");
parm = (iparml_set_mask *)grab_param();
parm->ipmask = *((__u8*)result);
@@ -2229,10 +2231,7 @@

u.param = SetMaskFlag;
cpu = get_cpu();
- if (cpu == iucv_cpuid)
- iucv_setmask_cpuid(&u);
- else
- smp_call_function(iucv_setmask_cpuid, &u, 0, 1);
+ smp_call_function_on(iucv_setmask_cpuid, &u, 0, 1, iucv_cpuid);
put_cpu();

return u.result;
@@ -2361,7 +2360,7 @@
iucv_dumpit("temp_buff2",
temp_buff2, sizeof(temp_buff2));

- if (memcmp (temp_buff1, temp_buff2, 24) == 0) {
+ if (!memcmp (temp_buff1, temp_buff2, 24)) {

iucv_debug(2,
"found a matching handler");
diff -urN linux-2.6/include/asm-s390/smp.h linux-2.6-s390/include/asm-s390/smp.h
--- linux-2.6/include/asm-s390/smp.h Fri Jul 9 18:58:46 2004
+++ linux-2.6-s390/include/asm-s390/smp.h Fri Jul 9 18:58:54 2004
@@ -69,7 +69,13 @@
#endif

#ifndef CONFIG_SMP
-#define smp_call_function_on(func,info,nonatomic,wait,cpu) ({ 0; })
+static inline int
+smp_call_function_on(void (*func) (void *info), void *info,
+ int nonatomic, int wait, int cpu)
+{
+ func(info);
+ return 0;
+}
#define smp_get_cpu(cpu) ({ 0; })
#define smp_put_cpu(cpu) ({ 0; })
#endif
-
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