[PATCH] i386: convert mm_context_t semaphore to a mutex

[PATCH] i386: convert mm_context_t semaphore to a mutex

[Luiz Fernando N. Capitulino]

Signed-off-by: Luiz Fernando N. Capitulino <lcapitulino@mandriva.com.br>
---
 arch/i386/kernel/i386_ksyms.c |    1 +
 arch/i386/kernel/ldt.c        |   14 +++++++-------
 arch/i386/kernel/ptrace.c     |    4 ++--
 include/asm-i386/mmu.h        |    4 ++--
 4 files changed, 12 insertions(+), 11 deletions(-)

--- linux-2.6-lcpt.orig/arch/i386/kernel/ldt.c
+++ linux-2.6-lcpt/arch/i386/kernel/ldt.c
@@ -94,13 +94,13 @@ int init_new_context(struct task_struct 
 	struct mm_struct * old_mm;
 	int retval = 0;
 
-	init_MUTEX(&mm->context.sem);
+	mutex_init(&mm->context.lock);
 	mm->context.size = 0;
 	old_mm = current->mm;
 	if (old_mm && old_mm->context.size > 0) {
-		down(&old_mm->context.sem);
+		mutex_lock(&old_mm->context.lock);
 		retval = copy_ldt(&mm->context, &old_mm->context);
-		up(&old_mm->context.sem);
+		mutex_unlock(&old_mm->context.lock);
 	}
 	return retval;
 }
@@ -132,7 +132,7 @@ static int read_ldt(void __user * ptr, u
 	if (bytecount > LDT_ENTRY_SIZE*LDT_ENTRIES)
 		bytecount = LDT_ENTRY_SIZE*LDT_ENTRIES;
 
-	down(&mm->context.sem);
+	mutex_lock(&mm->context.lock);
 	size = mm->context.size*LDT_ENTRY_SIZE;
 	if (size > bytecount)
 		size = bytecount;
@@ -140,7 +140,7 @@ static int read_ldt(void __user * ptr, u
 	err = 0;
 	if (copy_to_user(ptr, mm->context.ldt, size))
 		err = -EFAULT;
-	up(&mm->context.sem);
+	mutex_unlock(&mm->context.lock);
 	if (err < 0)
 		goto error_return;
 	if (size != bytecount) {
@@ -196,7 +196,7 @@ static int write_ldt(void __user * ptr, 
 			goto out;
 	}
 
-	down(&mm->context.sem);
+	mutex_lock(&mm->context.lock);
 	if (ldt_info.entry_number >= mm->context.size) {
 		error = alloc_ldt(&current->mm->context, ldt_info.entry_number+1, 1);
 		if (error < 0)
@@ -223,7 +223,7 @@ install:
 	error = 0;
 
 out_unlock:
-	up(&mm->context.sem);
+	mutex_unlock(&mm->context.lock);
 out:
 	return error;
 }
--- linux-2.6-lcpt.orig/arch/i386/kernel/ptrace.c
+++ linux-2.6-lcpt/arch/i386/kernel/ptrace.c
@@ -166,7 +166,7 @@ static unsigned long convert_eip_to_line
 
 		seg &= ~7UL;
 
-		down(&child->mm->context.sem);
+		mutex_lock(&child->mm->context.lock);
 		if (unlikely((seg >> 3) >= child->mm->context.size))
 			addr = -1L; /* bogus selector, access would fault */
 		else {
@@ -180,7 +180,7 @@ static unsigned long convert_eip_to_line
 				addr &= 0xffff;
 			addr += base;
 		}
-		up(&child->mm->context.sem);
+		mutex_unlock(&child->mm->context.lock);
 	}
 	return addr;
 }
--- linux-2.6-lcpt.orig/include/asm-i386/mmu.h
+++ linux-2.6-lcpt/include/asm-i386/mmu.h
@@ -1,7 +1,7 @@
 #ifndef __i386_MMU_H
 #define __i386_MMU_H
 
-#include <asm/semaphore.h>
+#include <linux/mutex.h>
 /*
  * The i386 doesn't have a mmu context, but
  * we put the segment information here.
@@ -10,7 +10,7 @@
  */
 typedef struct { 
 	int size;
-	struct semaphore sem;
+	struct mutex lock;
 	void *ldt;
 	void *vdso;
 } mm_context_t;
--- linux-2.6-lcpt.orig/arch/i386/kernel/i386_ksyms.c
+++ linux-2.6-lcpt/arch/i386/kernel/i386_ksyms.c
@@ -1,4 +1,5 @@
 #include <linux/module.h>
+#include <asm/semaphore.h>
 #include <asm/checksum.h>
 #include <asm/desc.h>
 


-- 
Luiz Fernando N. Capitulino

Re: [PATCH] i386: convert mm_context_t semaphore to a mutex

[Ingo Molnar]

>  typedef struct { 
>  	int size;
> -	struct semaphore sem;
> +	struct mutex lock;

hm, looks good to me but i'm wondering why this was a holdout for such a 
long time :-) Did you manage to test actual LDT functionality with this 
patch applied?

	Ingo

Re: [PATCH] i386: convert mm_context_t semaphore to a mutex

[Luiz Fernando N. Capitulino]

Em Mon, 6 Aug 2007 09:46:08 +0200
Ingo Molnar <mingo@elte.hu> escreveu:

| 
| >  typedef struct { 
| >  	int size;
| > -	struct semaphore sem;
| > +	struct mutex lock;
| 
| hm, looks good to me but i'm wondering why this was a holdout for such a 
| long time :-) Did you manage to test actual LDT functionality with this 
| patch applied?

 No, I didn't. The only test I did was to run the kernel with this
patch applied.

 I'll manage to test it then. Do you have a test-case or has any
suggestion?

 Oh, btw, I forgot to 'quilt add arch/i386/mm/fault.c' so the
patch I sent was incomplete. Fixed version below. Shame on me.

[PATCH] i386: convert mm_context_t semaphore to a mutex

---
 arch/i386/kernel/i386_ksyms.c |    1 +
 arch/i386/kernel/ldt.c        |   14 +++++++-------
 arch/i386/kernel/ptrace.c     |    4 ++--
 arch/i386/mm/fault.c          |    4 ++--
 include/asm-i386/mmu.h        |    4 ++--
 5 files changed, 14 insertions(+), 13 deletions(-)

--- linux-2.6-lcpt.orig/arch/i386/kernel/ldt.c
+++ linux-2.6-lcpt/arch/i386/kernel/ldt.c
@@ -94,13 +94,13 @@ int init_new_context(struct task_struct 
 	struct mm_struct * old_mm;
 	int retval = 0;
 
-	init_MUTEX(&mm->context.sem);
+	mutex_init(&mm->context.lock);
 	mm->context.size = 0;
 	old_mm = current->mm;
 	if (old_mm && old_mm->context.size > 0) {
-		down(&old_mm->context.sem);
+		mutex_lock(&old_mm->context.lock);
 		retval = copy_ldt(&mm->context, &old_mm->context);
-		up(&old_mm->context.sem);
+		mutex_unlock(&old_mm->context.lock);
 	}
 	return retval;
 }
@@ -132,7 +132,7 @@ static int read_ldt(void __user * ptr, u
 	if (bytecount > LDT_ENTRY_SIZE*LDT_ENTRIES)
 		bytecount = LDT_ENTRY_SIZE*LDT_ENTRIES;
 
-	down(&mm->context.sem);
+	mutex_lock(&mm->context.lock);
 	size = mm->context.size*LDT_ENTRY_SIZE;
 	if (size > bytecount)
 		size = bytecount;
@@ -140,7 +140,7 @@ static int read_ldt(void __user * ptr, u
 	err = 0;
 	if (copy_to_user(ptr, mm->context.ldt, size))
 		err = -EFAULT;
-	up(&mm->context.sem);
+	mutex_unlock(&mm->context.lock);
 	if (err < 0)
 		goto error_return;
 	if (size != bytecount) {
@@ -196,7 +196,7 @@ static int write_ldt(void __user * ptr, 
 			goto out;
 	}
 
-	down(&mm->context.sem);
+	mutex_lock(&mm->context.lock);
 	if (ldt_info.entry_number >= mm->context.size) {
 		error = alloc_ldt(&current->mm->context, ldt_info.entry_number+1, 1);
 		if (error < 0)
@@ -223,7 +223,7 @@ install:
 	error = 0;
 
 out_unlock:
-	up(&mm->context.sem);
+	mutex_unlock(&mm->context.lock);
 out:
 	return error;
 }
--- linux-2.6-lcpt.orig/arch/i386/kernel/ptrace.c
+++ linux-2.6-lcpt/arch/i386/kernel/ptrace.c
@@ -166,7 +166,7 @@ static unsigned long convert_eip_to_line
 
 		seg &= ~7UL;
 
-		down(&child->mm->context.sem);
+		mutex_lock(&child->mm->context.lock);
 		if (unlikely((seg >> 3) >= child->mm->context.size))
 			addr = -1L; /* bogus selector, access would fault */
 		else {
@@ -180,7 +180,7 @@ static unsigned long convert_eip_to_line
 				addr &= 0xffff;
 			addr += base;
 		}
-		up(&child->mm->context.sem);
+		mutex_unlock(&child->mm->context.lock);
 	}
 	return addr;
 }
--- linux-2.6-lcpt.orig/include/asm-i386/mmu.h
+++ linux-2.6-lcpt/include/asm-i386/mmu.h
@@ -1,7 +1,7 @@
 #ifndef __i386_MMU_H
 #define __i386_MMU_H
 
-#include <asm/semaphore.h>
+#include <linux/mutex.h>
 /*
  * The i386 doesn't have a mmu context, but
  * we put the segment information here.
@@ -10,7 +10,7 @@
  */
 typedef struct { 
 	int size;
-	struct semaphore sem;
+	struct mutex lock;
 	void *ldt;
 	void *vdso;
 } mm_context_t;
--- linux-2.6-lcpt.orig/arch/i386/kernel/i386_ksyms.c
+++ linux-2.6-lcpt/arch/i386/kernel/i386_ksyms.c
@@ -1,4 +1,5 @@
 #include <linux/module.h>
+#include <asm/semaphore.h>
 #include <asm/checksum.h>
 #include <asm/desc.h>
 
--- linux-2.6-lcpt.orig/arch/i386/mm/fault.c
+++ linux-2.6-lcpt/arch/i386/mm/fault.c
@@ -110,7 +110,7 @@ static inline unsigned long get_segment_
 	   LDT and other horrors are only used in user space. */
 	if (seg & (1<<2)) {
 		/* Must lock the LDT while reading it. */
-		down(&current->mm->context.sem);
+		mutex_lock(&current->mm->context.lock);
 		desc = current->mm->context.ldt;
 		desc = (void *)desc + (seg & ~7);
 	} else {
@@ -123,7 +123,7 @@ static inline unsigned long get_segment_
 	base = get_desc_base((unsigned long *)desc);
 
 	if (seg & (1<<2)) { 
-		up(&current->mm->context.sem);
+		mutex_unlock(&current->mm->context.lock);
 	} else
 		put_cpu();
 


-- 
Luiz Fernando N. Capitulino

Re: [PATCH] i386: convert mm_context_t semaphore to a mutex

[Luiz Fernando N. Capitulino]

Em Mon, 6 Aug 2007 09:46:08 +0200
Ingo Molnar <mingo@elte.hu> escreveu:

| 
| >  typedef struct { 
| >  	int size;
| > -	struct semaphore sem;
| > +	struct mutex lock;
| 
| hm, looks good to me but i'm wondering why this was a holdout for such a 
| long time :-) Did you manage to test actual LDT functionality with this 
| patch applied?

 No, I didn't. The only test I did was to run the kernel with this
patch applied.

 I'll manage to test it then. Do you have a test-case or has any
suggestion?

 Oh, btw, I forgot to 'quilt add arch/i386/mm/fault.c' so the
patch I sent was incomplete. Fixed version below. Shame on me.

[PATCH] i386: convert mm_context_t semaphore to a mutex

---
 arch/i386/kernel/i386_ksyms.c |    1 +
 arch/i386/kernel/ldt.c        |   14 +++++++-------
 arch/i386/kernel/ptrace.c     |    4 ++--
 arch/i386/mm/fault.c          |    4 ++--
 include/asm-i386/mmu.h        |    4 ++--
 5 files changed, 14 insertions(+), 13 deletions(-)

--- linux-2.6-lcpt.orig/arch/i386/kernel/ldt.c
+++ linux-2.6-lcpt/arch/i386/kernel/ldt.c
@@ -94,13 +94,13 @@ int init_new_context(struct task_struct 
 	struct mm_struct * old_mm;
 	int retval = 0;
 
-	init_MUTEX(&mm->context.sem);
+	mutex_init(&mm->context.lock);
 	mm->context.size = 0;
 	old_mm = current->mm;
 	if (old_mm && old_mm->context.size > 0) {
-		down(&old_mm->context.sem);
+		mutex_lock(&old_mm->context.lock);
 		retval = copy_ldt(&mm->context, &old_mm->context);
-		up(&old_mm->context.sem);
+		mutex_unlock(&old_mm->context.lock);
 	}
 	return retval;
 }
@@ -132,7 +132,7 @@ static int read_ldt(void __user * ptr, u
 	if (bytecount > LDT_ENTRY_SIZE*LDT_ENTRIES)
 		bytecount = LDT_ENTRY_SIZE*LDT_ENTRIES;
 
-	down(&mm->context.sem);
+	mutex_lock(&mm->context.lock);
 	size = mm->context.size*LDT_ENTRY_SIZE;
 	if (size > bytecount)
 		size = bytecount;
@@ -140,7 +140,7 @@ static int read_ldt(void __user * ptr, u
 	err = 0;
 	if (copy_to_user(ptr, mm->context.ldt, size))
 		err = -EFAULT;
-	up(&mm->context.sem);
+	mutex_unlock(&mm->context.lock);
 	if (err < 0)
 		goto error_return;
 	if (size != bytecount) {
@@ -196,7 +196,7 @@ static int write_ldt(void __user * ptr, 
 			goto out;
 	}
 
-	down(&mm->context.sem);
+	mutex_lock(&mm->context.lock);
 	if (ldt_info.entry_number >= mm->context.size) {
 		error = alloc_ldt(&current->mm->context, ldt_info.entry_number+1, 1);
 		if (error < 0)
@@ -223,7 +223,7 @@ install:
 	error = 0;
 
 out_unlock:
-	up(&mm->context.sem);
+	mutex_unlock(&mm->context.lock);
 out:
 	return error;
 }
--- linux-2.6-lcpt.orig/arch/i386/kernel/ptrace.c
+++ linux-2.6-lcpt/arch/i386/kernel/ptrace.c
@@ -166,7 +166,7 @@ static unsigned long convert_eip_to_line
 
 		seg &= ~7UL;
 
-		down(&child->mm->context.sem);
+		mutex_lock(&child->mm->context.lock);
 		if (unlikely((seg >> 3) >= child->mm->context.size))
 			addr = -1L; /* bogus selector, access would fault */
 		else {
@@ -180,7 +180,7 @@ static unsigned long convert_eip_to_line
 				addr &= 0xffff;
 			addr += base;
 		}
-		up(&child->mm->context.sem);
+		mutex_unlock(&child->mm->context.lock);
 	}
 	return addr;
 }
--- linux-2.6-lcpt.orig/include/asm-i386/mmu.h
+++ linux-2.6-lcpt/include/asm-i386/mmu.h
@@ -1,7 +1,7 @@
 #ifndef __i386_MMU_H
 #define __i386_MMU_H
 
-#include <asm/semaphore.h>
+#include <linux/mutex.h>
 /*
  * The i386 doesn't have a mmu context, but
  * we put the segment information here.
@@ -10,7 +10,7 @@
  */
 typedef struct { 
 	int size;
-	struct semaphore sem;
+	struct mutex lock;
 	void *ldt;
 	void *vdso;
 } mm_context_t;
--- linux-2.6-lcpt.orig/arch/i386/kernel/i386_ksyms.c
+++ linux-2.6-lcpt/arch/i386/kernel/i386_ksyms.c
@@ -1,4 +1,5 @@
 #include <linux/module.h>
+#include <asm/semaphore.h>
 #include <asm/checksum.h>
 #include <asm/desc.h>
 
--- linux-2.6-lcpt.orig/arch/i386/mm/fault.c
+++ linux-2.6-lcpt/arch/i386/mm/fault.c
@@ -110,7 +110,7 @@ static inline unsigned long get_segment_
 	   LDT and other horrors are only used in user space. */
 	if (seg & (1<<2)) {
 		/* Must lock the LDT while reading it. */
-		down(&current->mm->context.sem);
+		mutex_lock(&current->mm->context.lock);
 		desc = current->mm->context.ldt;
 		desc = (void *)desc + (seg & ~7);
 	} else {
@@ -123,7 +123,7 @@ static inline unsigned long get_segment_
 	base = get_desc_base((unsigned long *)desc);
 
 	if (seg & (1<<2)) { 
-		up(&current->mm->context.sem);
+		mutex_unlock(&current->mm->context.lock);
 	} else
 		put_cpu();
 


-- 
Luiz Fernando N. Capitulino

Re: [PATCH] i386: convert mm_context_t semaphore to a mutex

[Ingo Molnar]

* Luiz Fernando N. Capitulino <lcapitulino@mandriva.com.br> wrote:

> | hm, looks good to me but i'm wondering why this was a holdout for 
> | such a long time :-) Did you manage to test actual LDT functionality 
> | with this patch applied?
> 
>  No, I didn't. The only test I did was to run the kernel with this 
> patch applied.
> 
>  I'll manage to test it then. Do you have a test-case or has any 
> suggestion?

i think try any pthread program with:

   export LD_ASSUME_KERNEL=2.4.0

should trigger the LDT code. Try stracing the code and modify_ldt calls 
should show up.

>  Oh, btw, I forgot to 'quilt add arch/i386/mm/fault.c' [...]

heh. After a dozen of such incidents i scripted my editor command to 
automatically do the quilt add :)

	Ingo

Re: [PATCH] i386: convert mm_context_t semaphore to a mutex

[Luiz Fernando N. Capitulino]

Em Mon, 6 Aug 2007 17:25:02 +0200
Ingo Molnar <mingo@elte.hu> escreveu:

| 
| * Luiz Fernando N. Capitulino <lcapitulino@mandriva.com.br> wrote:
| 
| > | hm, looks good to me but i'm wondering why this was a holdout for 
| > | such a long time :-) Did you manage to test actual LDT functionality 
| > | with this patch applied?
| > 
| >  No, I didn't. The only test I did was to run the kernel with this 
| > patch applied.
| > 
| >  I'll manage to test it then. Do you have a test-case or has any 
| > suggestion?
| 
| i think try any pthread program with:
| 
|    export LD_ASSUME_KERNEL=2.4.0
| 
| should trigger the LDT code. Try stracing the code and modify_ldt calls 
| should show up.

 I couldn't run this because my libc requires 2.6 kernels.

 But I've managed to run wine with a game called 'Align-it!', and
I have the following result:

"""
~/tmp/ egrep -c 'modify_ldt' wine-strace.txt 
46
~/tmp/ 
"""

 I've checked the calls and none has failed. Not sure how good
this test is though.

 Maybe it could be more tested in -mm?

| >  Oh, btw, I forgot to 'quilt add arch/i386/mm/fault.c' [...]
| 
| heh. After a dozen of such incidents i scripted my editor command to 
| automatically do the quilt add :)

 Oh, that's a good tip.

 Thanks a lot,

-- 
Luiz Fernando N. Capitulino

Re: [PATCH] i386: convert mm_context_t semaphore to a mutex

[Ingo Molnar]

* Luiz Fernando N. Capitulino <lcapitulino@mandriva.com.br> wrote:

>  But I've managed to run wine with a game called 'Align-it!', and
> I have the following result:
> 
> """
> ~/tmp/ egrep -c 'modify_ldt' wine-strace.txt 
> 46
> ~/tmp/ 
> """
> 
>  I've checked the calls and none has failed. Not sure how good
> this test is though.

ok, this is certainly good enough.

Acked-by: Ingo Molnar <mingo@elte.hu>

	Ingo

Re: [PATCH] i386: convert mm_context_t semaphore to a mutex

[Andi Kleen]

"Luiz Fernando N. Capitulino" <lcapitulino@mandriva.com.br> writes:
> 
>  I'll manage to test it then. Do you have a test-case or has any
> suggestion?

LTP has some simple test cases for modify_ldt

-Andi

Re: [PATCH] i386: convert mm_context_t semaphore to a mutex

[Luiz Fernando N. Capitulino]

Em 06 Aug 2007 21:32:29 +0200
Andi Kleen <andi@firstfloor.org> escreveu:

| "Luiz Fernando N. Capitulino" <lcapitulino@mandriva.com.br> writes:
| > 
| >  I'll manage to test it then. Do you have a test-case or has any
| > suggestion?
| 
| LTP has some simple test cases for modify_ldt

 I've just ran them from a LTP suite from 2007/04/30:

"""
/usr/lib/ltp/testcases/kernel/syscalls/modify_ldt/ ./modify_ldt01 
modify_ldt01    0  INFO  :  Enter block 1
modify_ldt01    0  INFO  :  block 1 PASSED
modify_ldt01    0  INFO  :  Exit block 1
modify_ldt01    0  INFO  :  Enter block 2
modify_ldt01    0  INFO  :  block 2 PASSED
modify_ldt01    0  INFO  :  Exit block 2
modify_ldt01    0  INFO  :  block 3 PASSED
modify_ldt01    0  INFO  :  Exit block 3
"""

"""
/usr/lib/ltp/testcases/kernel/syscalls/modify_ldt/ ./modify_ldt02
modify_ldt02    0  INFO  :  Enter block 1
modify_ldt02    0  INFO  :  block 1 PASSED
modify_ldt02    0  INFO  :  Exit block 1
modify_ldt02    0  INFO  :  Enter block 2
modify_ldt02    0  INFO  :  received signal: 11
modify_ldt02    0  INFO  :  block 2 PASSED
/usr/lib/ltp/testcases/kernel/syscalls/modify_ldt/ 
"""

 All passed it seems.

 Btw, I've send the same patch for x86_64 to you too.

-- 
Luiz Fernando N. Capitulino

Re: [PATCH] i386: convert mm_context_t semaphore to a mutex

[Luiz Fernando N. Capitulino]

Em Mon, 6 Aug 2007 09:46:08 +0200
Ingo Molnar <mingo@elte.hu> escreveu:

| 
| >  typedef struct { 
| >  	int size;
| > -	struct semaphore sem;
| > +	struct mutex lock;
| 
| hm, looks good to me but i'm wondering why this was a holdout for such a 
| long time :-) Did you manage to test actual LDT functionality with this 
| patch applied?

 No, I didn't. The only test I did was to run the kernel with this
patch applied.

 I'll manage to test it then. Do you have a test-case or has any
suggestion?

 Oh, btw, I forgot to 'quilt add arch/i386/mm/fault.c' so the
patch I sent was incomplete. Fixed version below. Shame on me.

[PATCH] i386: convert mm_context_t semaphore to a mutex

---
 arch/i386/kernel/i386_ksyms.c |    1 +
 arch/i386/kernel/ldt.c        |   14 +++++++-------
 arch/i386/kernel/ptrace.c     |    4 ++--
 arch/i386/mm/fault.c          |    4 ++--
 include/asm-i386/mmu.h        |    4 ++--
 5 files changed, 14 insertions(+), 13 deletions(-)

--- linux-2.6-lcpt.orig/arch/i386/kernel/ldt.c
+++ linux-2.6-lcpt/arch/i386/kernel/ldt.c
@@ -94,13 +94,13 @@ int init_new_context(struct task_struct 
 	struct mm_struct * old_mm;
 	int retval = 0;
 
-	init_MUTEX(&mm->context.sem);
+	mutex_init(&mm->context.lock);
 	mm->context.size = 0;
 	old_mm = current->mm;
 	if (old_mm && old_mm->context.size > 0) {
-		down(&old_mm->context.sem);
+		mutex_lock(&old_mm->context.lock);
 		retval = copy_ldt(&mm->context, &old_mm->context);
-		up(&old_mm->context.sem);
+		mutex_unlock(&old_mm->context.lock);
 	}
 	return retval;
 }
@@ -132,7 +132,7 @@ static int read_ldt(void __user * ptr, u
 	if (bytecount > LDT_ENTRY_SIZE*LDT_ENTRIES)
 		bytecount = LDT_ENTRY_SIZE*LDT_ENTRIES;
 
-	down(&mm->context.sem);
+	mutex_lock(&mm->context.lock);
 	size = mm->context.size*LDT_ENTRY_SIZE;
 	if (size > bytecount)
 		size = bytecount;
@@ -140,7 +140,7 @@ static int read_ldt(void __user * ptr, u
 	err = 0;
 	if (copy_to_user(ptr, mm->context.ldt, size))
 		err = -EFAULT;
-	up(&mm->context.sem);
+	mutex_unlock(&mm->context.lock);
 	if (err < 0)
 		goto error_return;
 	if (size != bytecount) {
@@ -196,7 +196,7 @@ static int write_ldt(void __user * ptr, 
 			goto out;
 	}
 
-	down(&mm->context.sem);
+	mutex_lock(&mm->context.lock);
 	if (ldt_info.entry_number >= mm->context.size) {
 		error = alloc_ldt(&current->mm->context, ldt_info.entry_number+1, 1);
 		if (error < 0)
@@ -223,7 +223,7 @@ install:
 	error = 0;
 
 out_unlock:
-	up(&mm->context.sem);
+	mutex_unlock(&mm->context.lock);
 out:
 	return error;
 }
--- linux-2.6-lcpt.orig/arch/i386/kernel/ptrace.c
+++ linux-2.6-lcpt/arch/i386/kernel/ptrace.c
@@ -166,7 +166,7 @@ static unsigned long convert_eip_to_line
 
 		seg &= ~7UL;
 
-		down(&child->mm->context.sem);
+		mutex_lock(&child->mm->context.lock);
 		if (unlikely((seg >> 3) >= child->mm->context.size))
 			addr = -1L; /* bogus selector, access would fault */
 		else {
@@ -180,7 +180,7 @@ static unsigned long convert_eip_to_line
 				addr &= 0xffff;
 			addr += base;
 		}
-		up(&child->mm->context.sem);
+		mutex_unlock(&child->mm->context.lock);
 	}
 	return addr;
 }
--- linux-2.6-lcpt.orig/include/asm-i386/mmu.h
+++ linux-2.6-lcpt/include/asm-i386/mmu.h
@@ -1,7 +1,7 @@
 #ifndef __i386_MMU_H
 #define __i386_MMU_H
 
-#include <asm/semaphore.h>
+#include <linux/mutex.h>
 /*
  * The i386 doesn't have a mmu context, but
  * we put the segment information here.
@@ -10,7 +10,7 @@
  */
 typedef struct { 
 	int size;
-	struct semaphore sem;
+	struct mutex lock;
 	void *ldt;
 	void *vdso;
 } mm_context_t;
--- linux-2.6-lcpt.orig/arch/i386/kernel/i386_ksyms.c
+++ linux-2.6-lcpt/arch/i386/kernel/i386_ksyms.c
@@ -1,4 +1,5 @@
 #include <linux/module.h>
+#include <asm/semaphore.h>
 #include <asm/checksum.h>
 #include <asm/desc.h>
 
--- linux-2.6-lcpt.orig/arch/i386/mm/fault.c
+++ linux-2.6-lcpt/arch/i386/mm/fault.c
@@ -110,7 +110,7 @@ static inline unsigned long get_segment_
 	   LDT and other horrors are only used in user space. */
 	if (seg & (1<<2)) {
 		/* Must lock the LDT while reading it. */
-		down(&current->mm->context.sem);
+		mutex_lock(&current->mm->context.lock);
 		desc = current->mm->context.ldt;
 		desc = (void *)desc + (seg & ~7);
 	} else {
@@ -123,7 +123,7 @@ static inline unsigned long get_segment_
 	base = get_desc_base((unsigned long *)desc);
 
 	if (seg & (1<<2)) { 
-		up(&current->mm->context.sem);
+		mutex_unlock(&current->mm->context.lock);
 	} else
 		put_cpu();
 


-- 
Luiz Fernando N. Capitulino

Re: [PATCH] i386: convert mm_context_t semaphore to a mutex

[Luiz Fernando N. Capitulino]

Em Mon, 6 Aug 2007 10:36:55 -0300
"Luiz Fernando N. Capitulino" <lcapitulino@mandriva.com.br> escreveu:

| Em Mon, 6 Aug 2007 09:46:08 +0200
| Ingo Molnar <mingo@elte.hu> escreveu:
| 
| | 
| | >  typedef struct { 
| | >  	int size;
| | > -	struct semaphore sem;
| | > +	struct mutex lock;
| | 
| | hm, looks good to me but i'm wondering why this was a holdout for such a 
| | long time :-) Did you manage to test actual LDT functionality with this 
| | patch applied?
| 
|  No, I didn't. The only test I did was to run the kernel with this
| patch applied.
| 
|  I'll manage to test it then. Do you have a test-case or has any
| suggestion?

 And again, SMTP problems makes me looks like a joker...

 Sorry for the spam, just realized the problem now.

-- 
Luiz Fernando N. Capitulino

Re: [PATCH] i386: convert mm_context_t semaphore to a mutex

[Luiz Fernando N. Capitulino]

Em Mon, 6 Aug 2007 09:46:08 +0200
Ingo Molnar <mingo@elte.hu> escreveu:

| 
| >  typedef struct { 
| >  	int size;
| > -	struct semaphore sem;
| > +	struct mutex lock;
| 
| hm, looks good to me but i'm wondering why this was a holdout for such a 
| long time :-) Did you manage to test actual LDT functionality with this 
| patch applied?

 No, I didn't. The only test I did was to run the kernel with this
patch applied.

 I'll manage to test it then. Do you have a test-case or has any
suggestion?

 Oh, btw, I forgot to 'quilt add arch/i386/mm/fault.c' so the
patch I sent was incomplete. Fixed version below. Shame on me.

[PATCH] i386: convert mm_context_t semaphore to a mutex

---
 arch/i386/kernel/i386_ksyms.c |    1 +
 arch/i386/kernel/ldt.c        |   14 +++++++-------
 arch/i386/kernel/ptrace.c     |    4 ++--
 arch/i386/mm/fault.c          |    4 ++--
 include/asm-i386/mmu.h        |    4 ++--
 5 files changed, 14 insertions(+), 13 deletions(-)

--- linux-2.6-lcpt.orig/arch/i386/kernel/ldt.c
+++ linux-2.6-lcpt/arch/i386/kernel/ldt.c
@@ -94,13 +94,13 @@ int init_new_context(struct task_struct 
 	struct mm_struct * old_mm;
 	int retval = 0;
 
-	init_MUTEX(&mm->context.sem);
+	mutex_init(&mm->context.lock);
 	mm->context.size = 0;
 	old_mm = current->mm;
 	if (old_mm && old_mm->context.size > 0) {
-		down(&old_mm->context.sem);
+		mutex_lock(&old_mm->context.lock);
 		retval = copy_ldt(&mm->context, &old_mm->context);
-		up(&old_mm->context.sem);
+		mutex_unlock(&old_mm->context.lock);
 	}
 	return retval;
 }
@@ -132,7 +132,7 @@ static int read_ldt(void __user * ptr, u
 	if (bytecount > LDT_ENTRY_SIZE*LDT_ENTRIES)
 		bytecount = LDT_ENTRY_SIZE*LDT_ENTRIES;
 
-	down(&mm->context.sem);
+	mutex_lock(&mm->context.lock);
 	size = mm->context.size*LDT_ENTRY_SIZE;
 	if (size > bytecount)
 		size = bytecount;
@@ -140,7 +140,7 @@ static int read_ldt(void __user * ptr, u
 	err = 0;
 	if (copy_to_user(ptr, mm->context.ldt, size))
 		err = -EFAULT;
-	up(&mm->context.sem);
+	mutex_unlock(&mm->context.lock);
 	if (err < 0)
 		goto error_return;
 	if (size != bytecount) {
@@ -196,7 +196,7 @@ static int write_ldt(void __user * ptr, 
 			goto out;
 	}
 
-	down(&mm->context.sem);
+	mutex_lock(&mm->context.lock);
 	if (ldt_info.entry_number >= mm->context.size) {
 		error = alloc_ldt(&current->mm->context, ldt_info.entry_number+1, 1);
 		if (error < 0)
@@ -223,7 +223,7 @@ install:
 	error = 0;
 
 out_unlock:
-	up(&mm->context.sem);
+	mutex_unlock(&mm->context.lock);
 out:
 	return error;
 }
--- linux-2.6-lcpt.orig/arch/i386/kernel/ptrace.c
+++ linux-2.6-lcpt/arch/i386/kernel/ptrace.c
@@ -166,7 +166,7 @@ static unsigned long convert_eip_to_line
 
 		seg &= ~7UL;
 
-		down(&child->mm->context.sem);
+		mutex_lock(&child->mm->context.lock);
 		if (unlikely((seg >> 3) >= child->mm->context.size))
 			addr = -1L; /* bogus selector, access would fault */
 		else {
@@ -180,7 +180,7 @@ static unsigned long convert_eip_to_line
 				addr &= 0xffff;
 			addr += base;
 		}
-		up(&child->mm->context.sem);
+		mutex_unlock(&child->mm->context.lock);
 	}
 	return addr;
 }
--- linux-2.6-lcpt.orig/include/asm-i386/mmu.h
+++ linux-2.6-lcpt/include/asm-i386/mmu.h
@@ -1,7 +1,7 @@
 #ifndef __i386_MMU_H
 #define __i386_MMU_H
 
-#include <asm/semaphore.h>
+#include <linux/mutex.h>
 /*
  * The i386 doesn't have a mmu context, but
  * we put the segment information here.
@@ -10,7 +10,7 @@
  */
 typedef struct { 
 	int size;
-	struct semaphore sem;
+	struct mutex lock;
 	void *ldt;
 	void *vdso;
 } mm_context_t;
--- linux-2.6-lcpt.orig/arch/i386/kernel/i386_ksyms.c
+++ linux-2.6-lcpt/arch/i386/kernel/i386_ksyms.c
@@ -1,4 +1,5 @@
 #include <linux/module.h>
+#include <asm/semaphore.h>
 #include <asm/checksum.h>
 #include <asm/desc.h>
 
--- linux-2.6-lcpt.orig/arch/i386/mm/fault.c
+++ linux-2.6-lcpt/arch/i386/mm/fault.c
@@ -110,7 +110,7 @@ static inline unsigned long get_segment_
 	   LDT and other horrors are only used in user space. */
 	if (seg & (1<<2)) {
 		/* Must lock the LDT while reading it. */
-		down(&current->mm->context.sem);
+		mutex_lock(&current->mm->context.lock);
 		desc = current->mm->context.ldt;
 		desc = (void *)desc + (seg & ~7);
 	} else {
@@ -123,7 +123,7 @@ static inline unsigned long get_segment_
 	base = get_desc_base((unsigned long *)desc);
 
 	if (seg & (1<<2)) { 
-		up(&current->mm->context.sem);
+		mutex_unlock(&current->mm->context.lock);
 	} else
 		put_cpu();
 


-- 
Luiz Fernando N. Capitulino