[PATCH 1/5] powerpc/mm: Handle hypervisor pte insert failure in __hash_page_huge

[PATCH 1/5] powerpc/mm: Handle hypervisor pte insert failure in __hash_page_huge

[Benjamin Herrenschmidt]

From: Anton Blanchard <anton@samba.org>

If the hypervisor gives us an error on a hugepage insert we panic. The
normal page code already handles this by returning an error instead and we end
calling low_hash_fault which will just kill the task if possible.

The patch below does a similar thing for the hugepage case.

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
---
 arch/powerpc/mm/hugetlbpage-hash64.c |   11 +++++++++--
 1 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/mm/hugetlbpage-hash64.c b/arch/powerpc/mm/hugetlbpage-hash64.c
index 1995398..c9acd79 100644
--- a/arch/powerpc/mm/hugetlbpage-hash64.c
+++ b/arch/powerpc/mm/hugetlbpage-hash64.c
@@ -121,8 +121,15 @@ repeat:
                         }
 		}
 
-		if (unlikely(slot == -2))
-			panic("hash_huge_page: pte_insert failed\n");
+		/*
+		 * Hypervisor failure. Restore old pte and return -1
+		 * similar to __hash_page_*
+		 */
+		if (unlikely(slot == -2)) {
+			*ptep = __pte(old_pte);
+			err = -1;
+			goto out;
+		}
 
 		new_pte |= (slot << 12) & (_PAGE_F_SECOND | _PAGE_F_GIX);
 	}
-- 
1.6.3.3

[PATCH 2/5] powerpc/mm: Move around testing of _PAGE_PRESENT in hash code

[Benjamin Herrenschmidt]

Instead of adding _PAGE_PRESENT to the access permission mask
in each low level routine independently, we add it once from
hash_page().

We also move the preliminary access check (the racy one before
the PTE is locked) up so it applies to the huge page case. This
duplicates code in __hash_page_huge() which we'll remove in a
subsequent patch to fix a race in there.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
---
 arch/powerpc/mm/hash_low_64.S   |    9 ---------
 arch/powerpc/mm/hash_utils_64.c |   19 +++++++++++--------
 2 files changed, 11 insertions(+), 17 deletions(-)

diff --git a/arch/powerpc/mm/hash_low_64.S b/arch/powerpc/mm/hash_low_64.S
index a719f53..3079f6b 100644
--- a/arch/powerpc/mm/hash_low_64.S
+++ b/arch/powerpc/mm/hash_low_64.S
@@ -68,9 +68,6 @@ _GLOBAL(__hash_page_4K)
 	std	r8,STK_PARM(r8)(r1)
 	std	r9,STK_PARM(r9)(r1)
 	
-	/* Add _PAGE_PRESENT to access */
-	ori	r4,r4,_PAGE_PRESENT
-
 	/* Save non-volatile registers.
 	 * r31 will hold "old PTE"
 	 * r30 is "new PTE"
@@ -347,9 +344,6 @@ _GLOBAL(__hash_page_4K)
 	std	r8,STK_PARM(r8)(r1)
 	std	r9,STK_PARM(r9)(r1)
 
-	/* Add _PAGE_PRESENT to access */
-	ori	r4,r4,_PAGE_PRESENT
-
 	/* Save non-volatile registers.
 	 * r31 will hold "old PTE"
 	 * r30 is "new PTE"
@@ -687,9 +681,6 @@ _GLOBAL(__hash_page_64K)
 	std	r8,STK_PARM(r8)(r1)
 	std	r9,STK_PARM(r9)(r1)
 
-	/* Add _PAGE_PRESENT to access */
-	ori	r4,r4,_PAGE_PRESENT
-
 	/* Save non-volatile registers.
 	 * r31 will hold "old PTE"
 	 * r30 is "new PTE"
diff --git a/arch/powerpc/mm/hash_utils_64.c b/arch/powerpc/mm/hash_utils_64.c
index 98f262d..40847a9 100644
--- a/arch/powerpc/mm/hash_utils_64.c
+++ b/arch/powerpc/mm/hash_utils_64.c
@@ -955,6 +955,17 @@ int hash_page(unsigned long ea, unsigned long access, unsigned long trap)
 		return 1;
 	}
 
+	/* Add _PAGE_PRESENT to the required access perm */
+	access |= _PAGE_PRESENT;
+
+	/* Pre-check access permissions (will be re-checked atomically
+	 * in __hash_page_XX but this pre-check is a fast path
+	 */
+	if (access & ~pte_val(*ptep)) {
+		DBG_LOW(" no access !\n");
+		return 1;
+	}
+
 #ifdef CONFIG_HUGETLB_PAGE
 	if (hugeshift)
 		return __hash_page_huge(ea, access, vsid, ptep, trap, local,
@@ -967,14 +978,6 @@ int hash_page(unsigned long ea, unsigned long access, unsigned long trap)
 	DBG_LOW(" i-pte: %016lx %016lx\n", pte_val(*ptep),
 		pte_val(*(ptep + PTRS_PER_PTE)));
 #endif
-	/* Pre-check access permissions (will be re-checked atomically
-	 * in __hash_page_XX but this pre-check is a fast path
-	 */
-	if (access & ~pte_val(*ptep)) {
-		DBG_LOW(" no access !\n");
-		return 1;
-	}
-
 	/* Do actual hashing */
 #ifdef CONFIG_PPC_64K_PAGES
 	/* If _PAGE_4K_PFN is set, make sure this is a 4k segment */
-- 
1.6.3.3

[PATCH 3/5] powerpc/mm: Fix bugs in huge page hashing

[Benjamin Herrenschmidt]

There's a couple of nasty bugs lurking in our huge page hashing code.

First, we don't check the access permission atomically with setting
the _PAGE_BUSY bit, which means that the PTE value we end up using
for the hashing might be different than the one we have checked
the access permissions for.

We've seen cases where that leads us to try to use an invalidated
PTE for hashing, causing all sort of "interesting" issues.

Then, we also failed to set _PAGE_DIRTY on a write access.

This fixes both, while also simplifying the code a bit.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
---
---
 arch/powerpc/mm/hugetlbpage-hash64.c |   31 +++++++++++++------------------
 1 files changed, 13 insertions(+), 18 deletions(-)

diff --git a/arch/powerpc/mm/hugetlbpage-hash64.c b/arch/powerpc/mm/hugetlbpage-hash64.c
index c9acd79..fd0a15e 100644
--- a/arch/powerpc/mm/hugetlbpage-hash64.c
+++ b/arch/powerpc/mm/hugetlbpage-hash64.c
@@ -21,21 +21,13 @@ int __hash_page_huge(unsigned long ea, unsigned long access, unsigned long vsid,
 	unsigned long old_pte, new_pte;
 	unsigned long va, rflags, pa, sz;
 	long slot;
-	int err = 1;
 
 	BUG_ON(shift != mmu_psize_defs[mmu_psize].shift);
 
 	/* Search the Linux page table for a match with va */
 	va = hpt_va(ea, vsid, ssize);
 
-	/*
-	 * Check the user's access rights to the page.  If access should be
-	 * prevented then send the problem up to do_page_fault.
-	 */
-	if (unlikely(access & ~pte_val(*ptep)))
-		goto out;
-	/*
-	 * At this point, we have a pte (old_pte) which can be used to build
+	/* At this point, we have a pte (old_pte) which can be used to build
 	 * or update an HPTE. There are 2 cases:
 	 *
 	 * 1. There is a valid (present) pte with no associated HPTE (this is
@@ -49,9 +41,17 @@ int __hash_page_huge(unsigned long ea, unsigned long access, unsigned long vsid,
 
 	do {
 		old_pte = pte_val(*ptep);
-		if (old_pte & _PAGE_BUSY)
-			goto out;
+		/* If PTE busy, retry the access */
+		if (unlikely(old_pte & _PAGE_BUSY))
+			return 0;
+		/* If PTE permissions don't match, take page fault */
+		if (unlikely(access & ~pte_val(*ptep)))
+			return 1;
+		/* Try to lock the PTE, add ACCESSED and DIRTY if it was
+		 * a write access */
 		new_pte = old_pte | _PAGE_BUSY | _PAGE_ACCESSED;
+		if (access & _PAGE_RW)
+			new_pte |= _PAGE_DIRTY;
 	} while(old_pte != __cmpxchg_u64((unsigned long *)ptep,
 					 old_pte, new_pte));
 
@@ -127,8 +127,7 @@ repeat:
 		 */
 		if (unlikely(slot == -2)) {
 			*ptep = __pte(old_pte);
-			err = -1;
-			goto out;
+			return -1;
 		}
 
 		new_pte |= (slot << 12) & (_PAGE_F_SECOND | _PAGE_F_GIX);
@@ -138,9 +137,5 @@ repeat:
 	 * No need to use ldarx/stdcx here
 	 */
 	*ptep = __pte(new_pte & ~_PAGE_BUSY);
-
-	err = 0;
-
- out:
-	return err;
+	return 0;
 }
-- 
1.6.3.3

[PATCH 4/5] powerpc/mm: Add some debug output when hash insertion fails

[Benjamin Herrenschmidt]

This adds some debug output to our MMU hash code to print out some
useful debug data if the hypervisor refuses the insertion (which
should normally never happen).

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
---
---
 arch/powerpc/include/asm/mmu-hash64.h |    4 ++-
 arch/powerpc/mm/hash_utils_64.c       |   34 ++++++++++++++++++++++++++++----
 arch/powerpc/mm/hugetlbpage-hash64.c  |    2 +
 3 files changed, 34 insertions(+), 6 deletions(-)

diff --git a/arch/powerpc/include/asm/mmu-hash64.h b/arch/powerpc/include/asm/mmu-hash64.h
index 2102b21..0e398cf 100644
--- a/arch/powerpc/include/asm/mmu-hash64.h
+++ b/arch/powerpc/include/asm/mmu-hash64.h
@@ -250,7 +250,9 @@ extern int hash_page(unsigned long ea, unsigned long access, unsigned long trap)
 int __hash_page_huge(unsigned long ea, unsigned long access, unsigned long vsid,
 		     pte_t *ptep, unsigned long trap, int local, int ssize,
 		     unsigned int shift, unsigned int mmu_psize);
-
+extern void hash_failure_debug(unsigned long ea, unsigned long access,
+			       unsigned long vsid, unsigned long trap,
+			       int ssize, int psize, unsigned long pte);
 extern int htab_bolt_mapping(unsigned long vstart, unsigned long vend,
 			     unsigned long pstart, unsigned long prot,
 			     int psize, int ssize);
diff --git a/arch/powerpc/mm/hash_utils_64.c b/arch/powerpc/mm/hash_utils_64.c
index 40847a9..09dffe6 100644
--- a/arch/powerpc/mm/hash_utils_64.c
+++ b/arch/powerpc/mm/hash_utils_64.c
@@ -871,6 +871,18 @@ static inline int subpage_protection(struct mm_struct *mm, unsigned long ea)
 }
 #endif
 
+void hash_failure_debug(unsigned long ea, unsigned long access,
+			unsigned long vsid, unsigned long trap,
+			int ssize, int psize, unsigned long pte)
+{
+	if (!printk_ratelimit())
+		return;
+	pr_info("mm: Hashing failure ! EA=0x%lx access=0x%lx current=%s\n",
+		ea, access, current->comm);
+	pr_info("    trap=0x%lx vsid=0x%lx ssize=%d psize=%d pte=0x%lx\n",
+		trap, vsid, ssize, psize, pte);
+}
+
 /* Result code is:
  *  0 - handled
  *  1 - normal page fault
@@ -1036,6 +1048,12 @@ int hash_page(unsigned long ea, unsigned long access, unsigned long trap)
 					    local, ssize, spp);
 	}
 
+	/* Dump some info in case of hash insertion failure, they should
+	 * never happen so it is really useful to know if/when they do
+	 */
+	if (rc == -1)
+		hash_failure_debug(ea, access, vsid, trap, ssize, psize,
+				   pte_val(*ptep));
 #ifndef CONFIG_PPC_64K_PAGES
 	DBG_LOW(" o-pte: %016lx\n", pte_val(*ptep));
 #else
@@ -1054,8 +1072,7 @@ void hash_preload(struct mm_struct *mm, unsigned long ea,
 	void *pgdir;
 	pte_t *ptep;
 	unsigned long flags;
-	int local = 0;
-	int ssize;
+	int rc, ssize, local = 0;
 
 	BUG_ON(REGION_ID(ea) != USER_REGION_ID);
 
@@ -1101,11 +1118,18 @@ void hash_preload(struct mm_struct *mm, unsigned long ea,
 	/* Hash it in */
 #ifdef CONFIG_PPC_HAS_HASH_64K
 	if (mm->context.user_psize == MMU_PAGE_64K)
-		__hash_page_64K(ea, access, vsid, ptep, trap, local, ssize);
+		rc = __hash_page_64K(ea, access, vsid, ptep, trap, local, ssize);
 	else
 #endif /* CONFIG_PPC_HAS_HASH_64K */
-		__hash_page_4K(ea, access, vsid, ptep, trap, local, ssize,
-			       subpage_protection(pgdir, ea));
+		rc = __hash_page_4K(ea, access, vsid, ptep, trap, local, ssize,
+				    subpage_protection(pgdir, ea));
+
+	/* Dump some info in case of hash insertion failure, they should
+	 * never happen so it is really useful to know if/when they do
+	 */
+	if (rc == -1)
+		hash_failure_debug(ea, access, vsid, trap, ssize,
+				   mm->context.user_psize, pte_val(*ptep));
 
 	local_irq_restore(flags);
 }
diff --git a/arch/powerpc/mm/hugetlbpage-hash64.c b/arch/powerpc/mm/hugetlbpage-hash64.c
index fd0a15e..db70c0d 100644
--- a/arch/powerpc/mm/hugetlbpage-hash64.c
+++ b/arch/powerpc/mm/hugetlbpage-hash64.c
@@ -127,6 +127,8 @@ repeat:
 		 */
 		if (unlikely(slot == -2)) {
 			*ptep = __pte(old_pte);
+			hash_failure_debug(ea, access, vsid, trap, ssize,
+					   mmu_psize, old_pte);
 			return -1;
 		}
 
-- 
1.6.3.3

[PATCH 5/5] powerpc: Fix erroneous lmb->memblock conversions

[Benjamin Herrenschmidt]

Oooops... we missed these. We incorrectly converted strings
used when parsing the device-tree on pseries, thus breaking
access to drconf memory and hotplug memory.

While at it, also revert some variable names that represent
something the FW calls "lmb" and thus don't need to be converted
to "memblock".

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
---
---
 arch/powerpc/kernel/prom.c                      |    2 +-
 arch/powerpc/mm/numa.c                          |   24 +++++++++++-----------
 arch/powerpc/platforms/pseries/hotplug-memory.c |   22 ++++++++++----------
 3 files changed, 24 insertions(+), 24 deletions(-)

diff --git a/arch/powerpc/kernel/prom.c b/arch/powerpc/kernel/prom.c
index 9d39539..fed9bf6 100644
--- a/arch/powerpc/kernel/prom.c
+++ b/arch/powerpc/kernel/prom.c
@@ -414,7 +414,7 @@ static int __init early_init_dt_scan_drconf_memory(unsigned long node)
 	u64 base, size, memblock_size;
 	unsigned int is_kexec_kdump = 0, rngs;
 
-	ls = of_get_flat_dt_prop(node, "ibm,memblock-size", &l);
+	ls = of_get_flat_dt_prop(node, "ibm,lmb-size", &l);
 	if (ls == NULL || l < dt_root_size_cells * sizeof(__be32))
 		return 0;
 	memblock_size = dt_mem_next_cell(dt_root_size_cells, &ls);
diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
index f473645..aa731af 100644
--- a/arch/powerpc/mm/numa.c
+++ b/arch/powerpc/mm/numa.c
@@ -398,15 +398,15 @@ static int of_get_drconf_memory(struct device_node *memory, const u32 **dm)
 }
 
 /*
- * Retreive and validate the ibm,memblock-size property for drconf memory
+ * Retreive and validate the ibm,lmb-size property for drconf memory
  * from the device tree.
  */
-static u64 of_get_memblock_size(struct device_node *memory)
+static u64 of_get_lmb_size(struct device_node *memory)
 {
 	const u32 *prop;
 	u32 len;
 
-	prop = of_get_property(memory, "ibm,memblock-size", &len);
+	prop = of_get_property(memory, "ibm,lmb-size", &len);
 	if (!prop || len < sizeof(unsigned int))
 		return 0;
 
@@ -562,7 +562,7 @@ static unsigned long __init numa_enforce_memory_limit(unsigned long start,
 static inline int __init read_usm_ranges(const u32 **usm)
 {
 	/*
-	 * For each memblock in ibm,dynamic-memory a corresponding
+	 * For each lmb in ibm,dynamic-memory a corresponding
 	 * entry in linux,drconf-usable-memory property contains
 	 * a counter followed by that many (base, size) duple.
 	 * read the counter from linux,drconf-usable-memory
@@ -578,7 +578,7 @@ static void __init parse_drconf_memory(struct device_node *memory)
 {
 	const u32 *dm, *usm;
 	unsigned int n, rc, ranges, is_kexec_kdump = 0;
-	unsigned long memblock_size, base, size, sz;
+	unsigned long lmb_size, base, size, sz;
 	int nid;
 	struct assoc_arrays aa;
 
@@ -586,8 +586,8 @@ static void __init parse_drconf_memory(struct device_node *memory)
 	if (!n)
 		return;
 
-	memblock_size = of_get_memblock_size(memory);
-	if (!memblock_size)
+	lmb_size = of_get_lmb_size(memory);
+	if (!lmb_size)
 		return;
 
 	rc = of_get_assoc_arrays(memory, &aa);
@@ -611,7 +611,7 @@ static void __init parse_drconf_memory(struct device_node *memory)
 			continue;
 
 		base = drmem.base_addr;
-		size = memblock_size;
+		size = lmb_size;
 		ranges = 1;
 
 		if (is_kexec_kdump) {
@@ -1072,7 +1072,7 @@ static int hot_add_drconf_scn_to_nid(struct device_node *memory,
 {
 	const u32 *dm;
 	unsigned int drconf_cell_cnt, rc;
-	unsigned long memblock_size;
+	unsigned long lmb_size;
 	struct assoc_arrays aa;
 	int nid = -1;
 
@@ -1080,8 +1080,8 @@ static int hot_add_drconf_scn_to_nid(struct device_node *memory,
 	if (!drconf_cell_cnt)
 		return -1;
 
-	memblock_size = of_get_memblock_size(memory);
-	if (!memblock_size)
+	lmb_size = of_get_lmb_size(memory);
+	if (!lmb_size)
 		return -1;
 
 	rc = of_get_assoc_arrays(memory, &aa);
@@ -1100,7 +1100,7 @@ static int hot_add_drconf_scn_to_nid(struct device_node *memory,
 			continue;
 
 		if ((scn_addr < drmem.base_addr)
-		    || (scn_addr >= (drmem.base_addr + memblock_size)))
+		    || (scn_addr >= (drmem.base_addr + lmb_size)))
 			continue;
 
 		nid = of_drconf_to_nid_single(&drmem, &aa);
diff --git a/arch/powerpc/platforms/pseries/hotplug-memory.c b/arch/powerpc/platforms/pseries/hotplug-memory.c
index deab5f9..bc88036 100644
--- a/arch/powerpc/platforms/pseries/hotplug-memory.c
+++ b/arch/powerpc/platforms/pseries/hotplug-memory.c
@@ -69,7 +69,7 @@ static int pseries_remove_memory(struct device_node *np)
 	const char *type;
 	const unsigned int *regs;
 	unsigned long base;
-	unsigned int memblock_size;
+	unsigned int lmb_size;
 	int ret = -EINVAL;
 
 	/*
@@ -87,9 +87,9 @@ static int pseries_remove_memory(struct device_node *np)
 		return ret;
 
 	base = *(unsigned long *)regs;
-	memblock_size = regs[3];
+	lmb_size = regs[3];
 
-	ret = pseries_remove_memblock(base, memblock_size);
+	ret = pseries_remove_memblock(base, lmb_size);
 	return ret;
 }
 
@@ -98,7 +98,7 @@ static int pseries_add_memory(struct device_node *np)
 	const char *type;
 	const unsigned int *regs;
 	unsigned long base;
-	unsigned int memblock_size;
+	unsigned int lmb_size;
 	int ret = -EINVAL;
 
 	/*
@@ -116,36 +116,36 @@ static int pseries_add_memory(struct device_node *np)
 		return ret;
 
 	base = *(unsigned long *)regs;
-	memblock_size = regs[3];
+	lmb_size = regs[3];
 
 	/*
 	 * Update memory region to represent the memory add
 	 */
-	ret = memblock_add(base, memblock_size);
+	ret = memblock_add(base, lmb_size);
 	return (ret < 0) ? -EINVAL : 0;
 }
 
 static int pseries_drconf_memory(unsigned long *base, unsigned int action)
 {
 	struct device_node *np;
-	const unsigned long *memblock_size;
+	const unsigned long *lmb_size;
 	int rc;
 
 	np = of_find_node_by_path("/ibm,dynamic-reconfiguration-memory");
 	if (!np)
 		return -EINVAL;
 
-	memblock_size = of_get_property(np, "ibm,memblock-size", NULL);
-	if (!memblock_size) {
+	lmb_size = of_get_property(np, "ibm,lmb-size", NULL);
+	if (!lmb_size) {
 		of_node_put(np);
 		return -EINVAL;
 	}
 
 	if (action == PSERIES_DRCONF_MEM_ADD) {
-		rc = memblock_add(*base, *memblock_size);
+		rc = memblock_add(*base, *lmb_size);
 		rc = (rc < 0) ? -EINVAL : 0;
 	} else if (action == PSERIES_DRCONF_MEM_REMOVE) {
-		rc = pseries_remove_memblock(*base, *memblock_size);
+		rc = pseries_remove_memblock(*base, *lmb_size);
 	} else {
 		rc = -EINVAL;
 	}
-- 
1.6.3.3

Re: [PATCH 3/5] powerpc/mm: Fix bugs in huge page hashing

[Benjamin Herrenschmidt]

On Fri, 2010-07-23 at 10:41 +1000, Benjamin Herrenschmidt wrote:
> There's a couple of nasty bugs lurking in our huge page hashing code.
> 
> First, we don't check the access permission atomically with setting
> the _PAGE_BUSY bit, which means that the PTE value we end up using
> for the hashing might be different than the one we have checked
> the access permissions for.
> 
> We've seen cases where that leads us to try to use an invalidated
> PTE for hashing, causing all sort of "interesting" issues.
> 
> Then, we also failed to set _PAGE_DIRTY on a write access.
> 
> This fixes both, while also simplifying the code a bit.

The changeset lacks a comment about a change to the return value
when hitting _PAGE_BUSY and ...

>  	do {
>  		old_pte = pte_val(*ptep);
> -		if (old_pte & _PAGE_BUSY)
> -			goto out;
> +		/* If PTE busy, retry the access */
> +		if (unlikely(old_pte & _PAGE_BUSY))
> +			return 0;
> +		/* If PTE permissions don't match, take page fault */
> +		if (unlikely(access & ~pte_val(*ptep)))
> +			return 1;

old_pte will do just fine instead of reloading it

Thanks Michael !

I'll respin that one.

Cheers,
Ben.

> +		/* Try to lock the PTE, add ACCESSED and DIRTY if it was
> +		 * a write access */
>  		new_pte = old_pte | _PAGE_BUSY | _PAGE_ACCESSED;
> +		if (access & _PAGE_RW)
> +			new_pte |= _PAGE_DIRTY;
>  	} while(old_pte != __cmpxchg_u64((unsigned long *)ptep,
>  					 old_pte, new_pte));
>  
> @@ -127,8 +127,7 @@ repeat:
>  		 */
>  		if (unlikely(slot == -2)) {
>  			*ptep = __pte(old_pte);
> -			err = -1;
> -			goto out;
> +			return -1;
>  		}
>  
>  		new_pte |= (slot << 12) & (_PAGE_F_SECOND | _PAGE_F_GIX);
> @@ -138,9 +137,5 @@ repeat:
>  	 * No need to use ldarx/stdcx here
>  	 */
>  	*ptep = __pte(new_pte & ~_PAGE_BUSY);
> -
> -	err = 0;
> -
> - out:
> -	return err;
> +	return 0;
>  }