[S390] cpcmd <-> __cpcmd calling issues

From: Martin Schwidefsky
Date: Mon Dec 04 2006 - 09:55:11 EST

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From: Heiko Carstens <heiko.carstens@xxxxxxxxxx>

[S390] cpcmd <-> __cpcmd calling issues

In case of reipl cpcmd gets called when all other cpus are not running
anymore. To prevent deadlocks change __cpcmd so that it doesn't take
any locks and call cpcmd or __cpcmd, whatever is correct in the current
context.

Signed-off-by: Heiko Carstens <heiko.carstens@xxxxxxxxxx>
Signed-off-by: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
---

arch/s390/kernel/cpcmd.c | 18 +++++++++++-------
arch/s390/kernel/ipl.c | 10 +++++-----
arch/s390/kernel/setup.c | 10 +++++-----
include/asm-s390/cpcmd.h | 10 +++-------
4 files changed, 24 insertions(+), 24 deletions(-)

diff -urpN linux-2.6/arch/s390/kernel/cpcmd.c linux-2.6-patched/arch/s390/kernel/cpcmd.c
--- linux-2.6/arch/s390/kernel/cpcmd.c 2006-11-29 22:57:37.000000000 +0100
+++ linux-2.6-patched/arch/s390/kernel/cpcmd.c 2006-12-04 14:50:49.000000000 +0100
@@ -21,14 +21,15 @@ static DEFINE_SPINLOCK(cpcmd_lock);
static char cpcmd_buf[241];

/*
- * the caller of __cpcmd has to ensure that the response buffer is below 2 GB
+ * __cpcmd has some restrictions over cpcmd
+ * - the response buffer must reside below 2GB (if any)
+ * - __cpcmd is unlocked and therefore not SMP-safe
*/
int __cpcmd(const char *cmd, char *response, int rlen, int *response_code)
{
- unsigned long flags, cmdlen;
+ unsigned cmdlen;
int return_code, return_len;

- spin_lock_irqsave(&cpcmd_lock, flags);
cmdlen = strlen(cmd);
BUG_ON(cmdlen > 240);
memcpy(cpcmd_buf, cmd, cmdlen);
@@ -74,7 +75,6 @@ int __cpcmd(const char *cmd, char *resp
: "+d" (reg3) : "d" (reg2) : "cc");
return_code = (int) reg3;
}
- spin_unlock_irqrestore(&cpcmd_lock, flags);
if (response_code != NULL)
*response_code = return_code;
return return_len;
@@ -82,15 +82,18 @@ int __cpcmd(const char *cmd, char *resp

EXPORT_SYMBOL(__cpcmd);

-#ifdef CONFIG_64BIT
int cpcmd(const char *cmd, char *response, int rlen, int *response_code)
{
char *lowbuf;
int len;
+ unsigned long flags;

if ((rlen == 0) || (response == NULL)
- || !((unsigned long)response >> 31))
+ || !((unsigned long)response >> 31)) {
+ spin_lock_irqsave(&cpcmd_lock, flags);
len = __cpcmd(cmd, response, rlen, response_code);
+ spin_unlock_irqrestore(&cpcmd_lock, flags);
+ }
else {
lowbuf = kmalloc(rlen, GFP_KERNEL | GFP_DMA);
if (!lowbuf) {
@@ -98,7 +101,9 @@ int cpcmd(const char *cmd, char *respons
"cpcmd: could not allocate response buffer\n");
return -ENOMEM;
}
+ spin_lock_irqsave(&cpcmd_lock, flags);
len = __cpcmd(cmd, lowbuf, rlen, response_code);
+ spin_unlock_irqrestore(&cpcmd_lock, flags);
memcpy(response, lowbuf, rlen);
kfree(lowbuf);
}
@@ -106,4 +111,3 @@ int cpcmd(const char *cmd, char *respons
}

EXPORT_SYMBOL(cpcmd);
-#endif /* CONFIG_64BIT */
diff -urpN linux-2.6/arch/s390/kernel/ipl.c linux-2.6-patched/arch/s390/kernel/ipl.c
--- linux-2.6/arch/s390/kernel/ipl.c 2006-12-04 14:50:48.000000000 +0100
+++ linux-2.6-patched/arch/s390/kernel/ipl.c 2006-12-04 14:50:49.000000000 +0100
@@ -677,7 +677,7 @@ void do_reipl(void)
else
sprintf(buf, "IPL %X LOADPARM '%s'",
reipl_block_ccw->ipl_info.ccw.devno, loadparm);
- cpcmd(buf, NULL, 0, NULL);
+ __cpcmd(buf, NULL, 0, NULL);
break;
case IPL_METHOD_CCW_DIAG:
diag308(DIAG308_SET, reipl_block_ccw);
@@ -691,12 +691,12 @@ void do_reipl(void)
diag308(DIAG308_IPL, NULL);
break;
case IPL_METHOD_FCP_RO_VM:
- cpcmd("IPL", NULL, 0, NULL);
+ __cpcmd("IPL", NULL, 0, NULL);
break;
case IPL_METHOD_NONE:
default:
if (MACHINE_IS_VM)
- cpcmd("IPL", NULL, 0, NULL);
+ __cpcmd("IPL", NULL, 0, NULL);
diag308(DIAG308_IPL, NULL);
break;
}
@@ -732,9 +732,9 @@ static void do_dump(void)
case IPL_METHOD_CCW_VM:
dump_smp_stop_all();
sprintf(buf, "STORE STATUS");
- cpcmd(buf, NULL, 0, NULL);
+ __cpcmd(buf, NULL, 0, NULL);
sprintf(buf, "IPL %X", dump_block_ccw->ipl_info.ccw.devno);
- cpcmd(buf, NULL, 0, NULL);
+ __cpcmd(buf, NULL, 0, NULL);
break;
case IPL_METHOD_CCW_DIAG:
diag308(DIAG308_SET, dump_block_ccw);
diff -urpN linux-2.6/arch/s390/kernel/setup.c linux-2.6-patched/arch/s390/kernel/setup.c
--- linux-2.6/arch/s390/kernel/setup.c 2006-11-29 22:57:37.000000000 +0100
+++ linux-2.6-patched/arch/s390/kernel/setup.c 2006-12-04 14:50:49.000000000 +0100
@@ -229,11 +229,11 @@ static void __init conmode_default(void)
char *ptr;

if (MACHINE_IS_VM) {
- __cpcmd("QUERY CONSOLE", query_buffer, 1024, NULL);
+ cpcmd("QUERY CONSOLE", query_buffer, 1024, NULL);
console_devno = simple_strtoul(query_buffer + 5, NULL, 16);
ptr = strstr(query_buffer, "SUBCHANNEL =");
console_irq = simple_strtoul(ptr + 13, NULL, 16);
- __cpcmd("QUERY TERM", query_buffer, 1024, NULL);
+ cpcmd("QUERY TERM", query_buffer, 1024, NULL);
ptr = strstr(query_buffer, "CONMODE");
/*
* Set the conmode to 3215 so that the device recognition
@@ -242,7 +242,7 @@ static void __init conmode_default(void)
* 3215 and the 3270 driver will try to access the console
* device (3215 as console and 3270 as normal tty).
*/
- __cpcmd("TERM CONMODE 3215", NULL, 0, NULL);
+ cpcmd("TERM CONMODE 3215", NULL, 0, NULL);
if (ptr == NULL) {
#if defined(CONFIG_SCLP_CONSOLE)
SET_CONSOLE_SCLP;
@@ -299,14 +299,14 @@ static void do_machine_restart_nonsmp(ch
static void do_machine_halt_nonsmp(void)
{
if (MACHINE_IS_VM && strlen(vmhalt_cmd) > 0)
- cpcmd(vmhalt_cmd, NULL, 0, NULL);
+ __cpcmd(vmhalt_cmd, NULL, 0, NULL);
signal_processor(smp_processor_id(), sigp_stop_and_store_status);
}

static void do_machine_power_off_nonsmp(void)
{
if (MACHINE_IS_VM && strlen(vmpoff_cmd) > 0)
- cpcmd(vmpoff_cmd, NULL, 0, NULL);
+ __cpcmd(vmpoff_cmd, NULL, 0, NULL);
signal_processor(smp_processor_id(), sigp_stop_and_store_status);
}

diff -urpN linux-2.6/include/asm-s390/cpcmd.h linux-2.6-patched/include/asm-s390/cpcmd.h
--- linux-2.6/include/asm-s390/cpcmd.h 2006-11-29 22:57:37.000000000 +0100
+++ linux-2.6-patched/include/asm-s390/cpcmd.h 2006-12-04 14:50:49.000000000 +0100
@@ -7,8 +7,8 @@
* Christian Borntraeger (cborntra@xxxxxxxxxx),
*/

-#ifndef __CPCMD__
-#define __CPCMD__
+#ifndef _ASM_S390_CPCMD_H
+#define _ASM_S390_CPCMD_H

/*
* the lowlevel function for cpcmd
@@ -16,9 +16,6 @@
*/
extern int __cpcmd(const char *cmd, char *response, int rlen, int *response_code);

-#ifndef __s390x__
-#define cpcmd __cpcmd
-#else
/*
* cpcmd is the in-kernel interface for issuing CP commands
*
@@ -33,6 +30,5 @@ extern int __cpcmd(const char *cmd, char
* NOTE: If the response buffer is not below 2 GB, cpcmd can sleep
*/
extern int cpcmd(const char *cmd, char *response, int rlen, int *response_code);
-#endif /*__s390x__*/

-#endif
+#endif /* _ASM_S390_CPCMD_H */
-
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Next message: Martin Schwidefsky: "[S390] Reset infrastructure for re-IPL."
Previous message: Martin Schwidefsky: "[S390] extmem unbalanced spin_lock."
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