[PATCH] PPC64: Janitor log_rtas_error() call arguments

[PATCH] PPC64: Janitor log_rtas_error() call arguments

[Paul Mackerras]

This patch from Linas Vepstas (rediffed by me) fixes the confusing
argument aliasing of the log_rtas_error() subroutine.

This patch makes no functional changes, it just cleans up some 
strange usage.

The rtas_args used to communicate with firmware are always taken
from the paca struct, so as to keep the args at a fixed, low-memory 
location.  But the log_rtas_error() routine also took an rtas_args
pointer, which it assumed was aliased to the paca struct.  This
aliasing is both un-neccessary, and confusing; this patch eliminates
this confusion.

Signed-off-by: Linas Vepstas <linas@linas.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

diff -urN linux-2.5/arch/ppc64/kernel/rtas.c ppc64-2.5-pseries/arch/ppc64/kernel/rtas.c
--- linux-2.5/arch/ppc64/kernel/rtas.c	2004-06-30 22:00:43.437979400 +1000
+++ ppc64-2.5-pseries/arch/ppc64/kernel/rtas.c	2004-06-30 21:55:51.000000000 +1000
@@ -75,9 +75,9 @@
 
 
 static int
-__log_rtas_error(struct rtas_args *rtas_args)
+__log_rtas_error(void)
 {
-	struct rtas_args err_args, temp_args;
+	struct rtas_args err_args, save_args;
 
 	err_args.token = rtas_token("rtas-last-error");
 	err_args.nargs = 2;
@@ -88,7 +88,7 @@
 	err_args.args[1] = RTAS_ERROR_LOG_MAX;
 	err_args.args[2] = 0;
 
-	temp_args = *rtas_args;
+	save_args = rtas.args;
 	rtas.args = err_args;
 
 	PPCDBG(PPCDBG_RTAS, "\tentering rtas with 0x%lx\n",
@@ -97,19 +97,19 @@
 	PPCDBG(PPCDBG_RTAS, "\treturned from rtas ...\n");
 
 	err_args = rtas.args;
-	rtas.args = temp_args;
+	rtas.args = save_args;
 
 	return err_args.rets[0];
 }
 
 void
-log_rtas_error(struct rtas_args	*rtas_args)
+log_rtas_error(void)
 {
 	unsigned long s;
 	int rc;
 
 	spin_lock_irqsave(&rtas.lock, s);
-	rc = __log_rtas_error(rtas_args);
+	rc = __log_rtas_error();
 	spin_unlock_irqrestore(&rtas.lock, s);
 	if (rc == 0)
 		log_error(rtas_err_buf, ERR_TYPE_RTAS_LOG, 0);
@@ -155,7 +155,7 @@
 	PPCDBG(PPCDBG_RTAS, "\treturned from rtas ...\n");
 
 	if (rtas_args->rets[0] == -1)
-		logit = (__log_rtas_error(rtas_args) == 0);
+		logit = (__log_rtas_error() == 0);
 
 	ifppcdebug(PPCDBG_RTAS) {
 		for(i=0; i < nret ;i++)
@@ -447,7 +447,7 @@
 
 	args.rets  = (rtas_arg_t *)&(args.args[nargs]);
 	if (args.rets[0] == -1)
-		log_rtas_error(&args);
+		log_rtas_error();
 
 	/* Copy out args. */
 	if (copy_to_user(uargs->args + nargs,

[PATCH] PPC64: Janitor log_rtas_error() call arguments

[linas]

[-- Attachment #1: Type: text/plain, Size: 708 bytes --]



Paul,

Please apply the following patch to the ameslab tree and/or forward to
the official 2.6 tree maintainers, as appropriate.  This patch fixes the 
confusing argument aliasing of the log_rtas_error() subroutine.  

This patch makes no functional changes, it just cleans up some 
strange usage.

The rtas_args used to communicate with firmware are always taken
from the paca struct, so as to keep the args at a fixed, low-memory 
location.  But the log_rtas_error() routine also took an rtas_args
pointer, which it assumed was aliased to the paca struct.  This
aliasing is both un-neccessary, and confusing; this patch eliminates
this confusion.

Signed-off-by: Linas Vepstas <linas@linas.org>

--linas

[-- Attachment #2: rtas-args-aliasing.patch --]
[-- Type: text/plain, Size: 1807 bytes --]

--- arch/ppc64/kernel/rtas.c.orig	2004-06-29 16:01:47.000000000 -0500
+++ arch/ppc64/kernel/rtas.c	2004-06-29 16:16:08.000000000 -0500
@@ -99,9 +99,9 @@ rtas_token(const char *service)
 
 
 static int
-__log_rtas_error(struct rtas_args *rtas_args)
+__log_rtas_error(void)
 {
-	struct rtas_args err_args, temp_args;
+	struct rtas_args err_args, save_args;
 
 	err_args.token = rtas_token("rtas-last-error");
 	err_args.nargs = 2;
@@ -112,7 +112,7 @@ __log_rtas_error(struct rtas_args *rtas_
 	err_args.args[1] = RTAS_ERROR_LOG_MAX;
 	err_args.args[2] = 0;
 
-	temp_args = *rtas_args;
+	save_args = get_paca()->xRtas;
 	get_paca()->xRtas = err_args;
 
 	PPCDBG(PPCDBG_RTAS, "\tentering rtas with 0x%lx\n",
@@ -121,19 +121,19 @@ __log_rtas_error(struct rtas_args *rtas_
 	PPCDBG(PPCDBG_RTAS, "\treturned from rtas ...\n");
 
 	err_args = get_paca()->xRtas;
-	get_paca()->xRtas = temp_args;
+	get_paca()->xRtas = save_args;
 
 	return err_args.rets[0];
 }
 
 void
-log_rtas_error(struct rtas_args	*rtas_args)
+log_rtas_error(void)
 {
 	unsigned long s;
 	int rc;
 
 	spin_lock_irqsave(&rtas.lock, s);
-	rc = __log_rtas_error(rtas_args);
+	rc = __log_rtas_error();
 	spin_unlock_irqrestore(&rtas.lock, s);
 	if (rc == 0)
 		log_error(rtas_err_buf, ERR_TYPE_RTAS_LOG, 0);
@@ -181,7 +181,7 @@ rtas_call(int token, int nargs, int nret
 	PPCDBG(PPCDBG_RTAS, "\treturned from rtas ...\n");
 
 	if (rtas_args->rets[0] == -1)
-		logit = (__log_rtas_error(rtas_args) == 0);
+		logit = (__log_rtas_error() == 0);
 
 	ifppcdebug(PPCDBG_RTAS) {
 		for(i=0; i < nret ;i++)
@@ -489,7 +489,7 @@ asmlinkage int ppc_rtas(struct rtas_args
 
 	args.rets  = (rtas_arg_t *)&(args.args[nargs]);
 	if (args.rets[0] == -1)
-		log_rtas_error(&args);
+		log_rtas_error();
 
 	/* Copy out args. */
 	if (copy_to_user(uargs->args + nargs,