Re: [PATCH kernel v3 2/4] powerpc/iommu: Stop using @current in mm_iommu_xxx

2016-10-20 Thread David Gibson 
On Thu, Oct 20, 2016 at 02:03:48PM +1100, Alexey Kardashevskiy wrote:
> This changes mm_iommu_xxx helpers to take mm_struct as a parameter
> instead of getting it from @current which in some situations may
> not have a valid reference to mm.
> 
> This changes helpers to receive @mm and moves all references to @current
> to the caller, including checks for !current and !current->mm;
> checks in mm_iommu_preregistered() are removed as there is no caller
> yet.
> 
> This moves the mm_iommu_adjust_locked_vm() call to the caller as
> it receives mm_iommu_table_group_mem_t but it needs mm.
> 
> This should cause no behavioral change.
> 
> Signed-off-by: Alexey Kardashevskiy 

Reviewed-by: David Gibson 

> ---
>  arch/powerpc/include/asm/mmu_context.h | 16 ++--
>  arch/powerpc/mm/mmu_context_iommu.c| 46 
> +-
>  drivers/vfio/vfio_iommu_spapr_tce.c| 14 ---
>  3 files changed, 36 insertions(+), 40 deletions(-)
> 
> diff --git a/arch/powerpc/include/asm/mmu_context.h 
> b/arch/powerpc/include/asm/mmu_context.h
> index 424844b..b9e3f0a 100644
> --- a/arch/powerpc/include/asm/mmu_context.h
> +++ b/arch/powerpc/include/asm/mmu_context.h
> @@ -19,16 +19,18 @@ extern void destroy_context(struct mm_struct *mm);
>  struct mm_iommu_table_group_mem_t;
>  
>  extern int isolate_lru_page(struct page *page);  /* from internal.h */
> -extern bool mm_iommu_preregistered(void);
> -extern long mm_iommu_get(unsigned long ua, unsigned long entries,
> +extern bool mm_iommu_preregistered(struct mm_struct *mm);
> +extern long mm_iommu_get(struct mm_struct *mm,
> + unsigned long ua, unsigned long entries,
>   struct mm_iommu_table_group_mem_t **pmem);
> -extern long mm_iommu_put(struct mm_iommu_table_group_mem_t *mem);
> +extern long mm_iommu_put(struct mm_struct *mm,
> + struct mm_iommu_table_group_mem_t *mem);
>  extern void mm_iommu_init(struct mm_struct *mm);
>  extern void mm_iommu_cleanup(struct mm_struct *mm);
> -extern struct mm_iommu_table_group_mem_t *mm_iommu_lookup(unsigned long ua,
> - unsigned long size);
> -extern struct mm_iommu_table_group_mem_t *mm_iommu_find(unsigned long ua,
> - unsigned long entries);
> +extern struct mm_iommu_table_group_mem_t *mm_iommu_lookup(struct mm_struct 
> *mm,
> + unsigned long ua, unsigned long size);
> +extern struct mm_iommu_table_group_mem_t *mm_iommu_find(struct mm_struct *mm,
> + unsigned long ua, unsigned long entries);
>  extern long mm_iommu_ua_to_hpa(struct mm_iommu_table_group_mem_t *mem,
>   unsigned long ua, unsigned long *hpa);
>  extern long mm_iommu_mapped_inc(struct mm_iommu_table_group_mem_t *mem);
> diff --git a/arch/powerpc/mm/mmu_context_iommu.c 
> b/arch/powerpc/mm/mmu_context_iommu.c
> index ad2e575..4c6db09 100644
> --- a/arch/powerpc/mm/mmu_context_iommu.c
> +++ b/arch/powerpc/mm/mmu_context_iommu.c
> @@ -56,7 +56,7 @@ static long mm_iommu_adjust_locked_vm(struct mm_struct *mm,
>   }
>  
>   pr_debug("[%d] RLIMIT_MEMLOCK HASH64 %c%ld %ld/%ld\n",
> - current->pid,
> + current ? current->pid : 0,
>   incr ? '+' : '-',
>   npages << PAGE_SHIFT,
>   mm->locked_vm << PAGE_SHIFT,
> @@ -66,12 +66,9 @@ static long mm_iommu_adjust_locked_vm(struct mm_struct *mm,
>   return ret;
>  }
>  
> -bool mm_iommu_preregistered(void)
> +bool mm_iommu_preregistered(struct mm_struct *mm)
>  {
> - if (!current || !current->mm)
> - return false;
> -
> - return !list_empty(¤t->mm->context.iommu_group_mem_list);
> + return !list_empty(&mm->context.iommu_group_mem_list);
>  }
>  EXPORT_SYMBOL_GPL(mm_iommu_preregistered);
>  
> @@ -124,19 +121,16 @@ static int mm_iommu_move_page_from_cma(struct page 
> *page)
>   return 0;
>  }
>  
> -long mm_iommu_get(unsigned long ua, unsigned long entries,
> +long mm_iommu_get(struct mm_struct *mm, unsigned long ua, unsigned long 
> entries,
>   struct mm_iommu_table_group_mem_t **pmem)
>  {
>   struct mm_iommu_table_group_mem_t *mem;
>   long i, j, ret = 0, locked_entries = 0;
>   struct page *page = NULL;
>  
> - if (!current || !current->mm)
> - return -ESRCH; /* process exited */
> -
>   mutex_lock(&mem_list_mutex);
>  
> - list_for_each_entry_rcu(mem, ¤t->mm->context.iommu_group_mem_list,
> + list_for_each_entry_rcu(mem, &mm->context.iommu_group_mem_list,
>   next) {
>   if ((mem->ua == ua) && (mem->entries == entries)) {
>   ++mem->used;
> @@ -154,7 +148,7 @@ long mm_iommu_get(unsigned long ua, unsigned long entries,
>  
>   }
>  
> - ret = mm_iommu_adjust_locked_vm(current->mm, entries, true);
> + ret = mm_iommu_adjust_locked_vm(mm, entries, true);
>   if (ret)
>   goto unlock_exit;
>  
> @@ -215,11 +209,11 @@ long mm_iommu_get(uns

[PATCH kernel v3 2/4] powerpc/iommu: Stop using @current in mm_iommu_xxx

2016-10-19 Thread Alexey Kardashevskiy 
This changes mm_iommu_xxx helpers to take mm_struct as a parameter
instead of getting it from @current which in some situations may
not have a valid reference to mm.

This changes helpers to receive @mm and moves all references to @current
to the caller, including checks for !current and !current->mm;
checks in mm_iommu_preregistered() are removed as there is no caller
yet.

This moves the mm_iommu_adjust_locked_vm() call to the caller as
it receives mm_iommu_table_group_mem_t but it needs mm.

This should cause no behavioral change.

Signed-off-by: Alexey Kardashevskiy 
---
 arch/powerpc/include/asm/mmu_context.h | 16 ++--
 arch/powerpc/mm/mmu_context_iommu.c| 46 +-
 drivers/vfio/vfio_iommu_spapr_tce.c| 14 ---
 3 files changed, 36 insertions(+), 40 deletions(-)

diff --git a/arch/powerpc/include/asm/mmu_context.h 
b/arch/powerpc/include/asm/mmu_context.h
index 424844b..b9e3f0a 100644
--- a/arch/powerpc/include/asm/mmu_context.h
+++ b/arch/powerpc/include/asm/mmu_context.h
@@ -19,16 +19,18 @@ extern void destroy_context(struct mm_struct *mm);
 struct mm_iommu_table_group_mem_t;
 
 extern int isolate_lru_page(struct page *page);/* from internal.h */
-extern bool mm_iommu_preregistered(void);
-extern long mm_iommu_get(unsigned long ua, unsigned long entries,
+extern bool mm_iommu_preregistered(struct mm_struct *mm);
+extern long mm_iommu_get(struct mm_struct *mm,
+   unsigned long ua, unsigned long entries,
struct mm_iommu_table_group_mem_t **pmem);
-extern long mm_iommu_put(struct mm_iommu_table_group_mem_t *mem);
+extern long mm_iommu_put(struct mm_struct *mm,
+   struct mm_iommu_table_group_mem_t *mem);
 extern void mm_iommu_init(struct mm_struct *mm);
 extern void mm_iommu_cleanup(struct mm_struct *mm);
-extern struct mm_iommu_table_group_mem_t *mm_iommu_lookup(unsigned long ua,
-   unsigned long size);
-extern struct mm_iommu_table_group_mem_t *mm_iommu_find(unsigned long ua,
-   unsigned long entries);
+extern struct mm_iommu_table_group_mem_t *mm_iommu_lookup(struct mm_struct *mm,
+   unsigned long ua, unsigned long size);
+extern struct mm_iommu_table_group_mem_t *mm_iommu_find(struct mm_struct *mm,
+   unsigned long ua, unsigned long entries);
 extern long mm_iommu_ua_to_hpa(struct mm_iommu_table_group_mem_t *mem,
unsigned long ua, unsigned long *hpa);
 extern long mm_iommu_mapped_inc(struct mm_iommu_table_group_mem_t *mem);
diff --git a/arch/powerpc/mm/mmu_context_iommu.c 
b/arch/powerpc/mm/mmu_context_iommu.c
index ad2e575..4c6db09 100644
--- a/arch/powerpc/mm/mmu_context_iommu.c
+++ b/arch/powerpc/mm/mmu_context_iommu.c
@@ -56,7 +56,7 @@ static long mm_iommu_adjust_locked_vm(struct mm_struct *mm,
}
 
pr_debug("[%d] RLIMIT_MEMLOCK HASH64 %c%ld %ld/%ld\n",
-   current->pid,
+   current ? current->pid : 0,
incr ? '+' : '-',
npages << PAGE_SHIFT,
mm->locked_vm << PAGE_SHIFT,
@@ -66,12 +66,9 @@ static long mm_iommu_adjust_locked_vm(struct mm_struct *mm,
return ret;
 }
 
-bool mm_iommu_preregistered(void)
+bool mm_iommu_preregistered(struct mm_struct *mm)
 {
-   if (!current || !current->mm)
-   return false;
-
-   return !list_empty(¤t->mm->context.iommu_group_mem_list);
+   return !list_empty(&mm->context.iommu_group_mem_list);
 }
 EXPORT_SYMBOL_GPL(mm_iommu_preregistered);
 
@@ -124,19 +121,16 @@ static int mm_iommu_move_page_from_cma(struct page *page)
return 0;
 }
 
-long mm_iommu_get(unsigned long ua, unsigned long entries,
+long mm_iommu_get(struct mm_struct *mm, unsigned long ua, unsigned long 
entries,
struct mm_iommu_table_group_mem_t **pmem)
 {
struct mm_iommu_table_group_mem_t *mem;
long i, j, ret = 0, locked_entries = 0;
struct page *page = NULL;
 
-   if (!current || !current->mm)
-   return -ESRCH; /* process exited */
-
mutex_lock(&mem_list_mutex);
 
-   list_for_each_entry_rcu(mem, ¤t->mm->context.iommu_group_mem_list,
+   list_for_each_entry_rcu(mem, &mm->context.iommu_group_mem_list,
next) {
if ((mem->ua == ua) && (mem->entries == entries)) {
++mem->used;
@@ -154,7 +148,7 @@ long mm_iommu_get(unsigned long ua, unsigned long entries,
 
}
 
-   ret = mm_iommu_adjust_locked_vm(current->mm, entries, true);
+   ret = mm_iommu_adjust_locked_vm(mm, entries, true);
if (ret)
goto unlock_exit;
 
@@ -215,11 +209,11 @@ long mm_iommu_get(unsigned long ua, unsigned long entries,
mem->entries = entries;
*pmem = mem;
 
-   list_add_rcu(&mem->next, ¤t->mm->context.iommu_group_mem_list);
+   list_add_rcu(&mem->next, &mm->context.iommu_group_mem_list);
 
 unlock_exit: