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UML - Remove unused variables in the context switcher

PATCH In review Jeff Dike 2 participants 3 messages Nov 14, 2007 – Nov 16, 2007

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Jeff Dike

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#0 lore raw

PATCH 2/4 UML - Remove unused variables in the context switcher

This patch removes a variable which was not used in two functions. Yet another code cleanup, nothing really significant.

Please note that I could not test this on x86_64. I don't have the hardware for it.

[ jdike - Bits of tidying around the affected code. Also, it's fine on x86_64 ]

---
 arch/um/kernel/process.c      |   19 ++++++++-----------
 arch/um/sys-i386/ptrace.c     |    6 +++---
 arch/um/sys-i386/tls.c        |    2 +-
 arch/um/sys-x86_64/syscalls.c |    2 +-
 4 files changed, 13 insertions(+), 16 deletions(-)
arch/um/kernel/process.c +8 -11
Index: linux-2.6.22/arch/um/kernel/process.c
===================================================================
@@ -82,12 +82,12 @@ static inline void set_current(struct ta
 		{ external_pid(task), task });
 }
 
-extern void arch_switch_to(struct task_struct *from, struct task_struct *to);
+extern void arch_switch_to(struct task_struct *to);
 
 void *_switch_to(void *prev, void *next, void *last)
 {
 	struct task_struct *from = prev;
-	struct task_struct *to= next;
+	struct task_struct *to = next;
 
 	to->thread.prev_sched = from;
 	set_current(to);
@@ -95,16 +95,15 @@ void *_switch_to(void *prev, void *next,
 	do {
 		current->thread.saved_task = NULL;
 
-		switch_threads(&from->thread.switch_buf,
-			       &to->thread.switch_buf);
+		switch_threads(&from->thread.switch_buf, &to->thread.switch_buf);
 
-		arch_switch_to(current->thread.prev_sched, current);
+		arch_switch_to(current);
 
 		if (current->thread.saved_task)
 			show_regs(&(current->thread.regs));
-		next= current->thread.saved_task;
-		prev= current;
-	} while(current->thread.saved_task);
+		next = current->thread.saved_task;
+		prev = current;
+	} while (current->thread.saved_task);
 
 	return current->thread.prev_sched;
 
@@ -162,8 +161,6 @@ void new_thread_handler(void)
 void fork_handler(void)
 {
 	force_flush_all();
-	if (current->thread.prev_sched == NULL)
-		panic("blech");
 
 	schedule_tail(current->thread.prev_sched);
 
@@ -172,7 +169,7 @@ void fork_handler(void)
 	 * arch_switch_to isn't needed. We could want to apply this to
 	 * improve performance. -bb
 	 */
-	arch_switch_to(current->thread.prev_sched, current);
+	arch_switch_to(current);
 
 	current->thread.prev_sched = NULL;
 
arch/um/sys-i386/ptrace.c +3 -3
Index: linux-2.6.22/arch/um/sys-i386/ptrace.c
===================================================================
@@ -8,11 +8,11 @@
 #include "asm/uaccess.h"
 #include "skas.h"
 
-extern int arch_switch_tls(struct task_struct *from, struct task_struct *to);
+extern int arch_switch_tls(struct task_struct *to);
 
-void arch_switch_to(struct task_struct *from, struct task_struct *to)
+void arch_switch_to(struct task_struct *to)
 {
-	int err = arch_switch_tls(from, to);
+	int err = arch_switch_tls(to);
 	if (!err)
 		return;
 
arch/um/sys-i386/tls.c +1 -1
Index: linux-2.6.22/arch/um/sys-i386/tls.c
===================================================================
@@ -172,7 +172,7 @@ void clear_flushed_tls(struct task_struc
  * SKAS patch.
  */
 
-int arch_switch_tls(struct task_struct *from, struct task_struct *to)
+int arch_switch_tls(struct task_struct *to)
 {
 	if (!host_supports_tls)
 		return 0;
arch/um/sys-x86_64/syscalls.c +1 -1
Index: linux-2.6.22/arch/um/sys-x86_64/syscalls.c
===================================================================
@@ -105,7 +105,7 @@ long sys_clone(unsigned long clone_flags
 	return ret;
 }
 
-void arch_switch_to(struct task_struct *from, struct task_struct *to)
+void arch_switch_to(struct task_struct *to)
 {
 	if ((to->thread.arch.fs == 0) || (to->mm == NULL))
 		return;

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#1 lore raw
Quoted 11 lines · On Wed, 14 Nov 2007 14:20:49 -0500 Jeff Dike <[email protected]> wrote:

This patch removes a variable which was not used in two functions. Yet another code cleanup, nothing really significant.

Please note that I could not test this on x86_64. I don't have the hardware for it.

[ jdike - Bits of tidying around the affected code. Also, it's fine on x86_64 ]

I assumed from the above that Karol was the author of this patch. Please let me know if that was wrong.

We communicate authorship by putting a From: line at the very start of the changelog. If that line is not present then we use the From: from the email headers.

Thanks.

author
#2 lore raw
Quoted 2 lines · Andrew Morton

I assumed from the above that Karol was the author of this patch. Please let me know if that was wrong.

He is - I forgot the From line...

Jeff

Signature · 1 line
Work email - jdike at linux dot intel dot com