powerpc/iommu: Stop using @current in mm_iommu_xxx

[ Upstream commit d7baee6901b34c4895eb78efdbf13a49079d7404 ]

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 <aik@ozlabs.ru>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Acked-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

2 files changed, 26 insertions, 36 deletions

diff --git a/arch/powerpc/include/asm/mmu_context.h b/arch/powerpc/include/asm/mmu_context.h
index 424844bc2a57..b9e3f0aca261 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 ad2e575fd418..4c6db09e77ad 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(&current->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, &current->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 @@ populate:
         mem->entries = entries;
         *pmem = mem;
 
-        list_add_rcu(&mem->next, &current->mm->context.iommu_group_mem_list);
+        list_add_rcu(&mem->next, &mm->context.iommu_group_mem_list);
 
 unlock_exit:
         if (locked_entries && ret)
-                mm_iommu_adjust_locked_vm(current->mm, locked_entries, false);
+                mm_iommu_adjust_locked_vm(mm, locked_entries, false);
 
         mutex_unlock(&mem_list_mutex);
 
@@ -264,17 +258,13 @@ static void mm_iommu_free(struct rcu_head *head)
 static void mm_iommu_release(struct mm_iommu_table_group_mem_t *mem)
 {
         list_del_rcu(&mem->next);
-        mm_iommu_adjust_locked_vm(current->mm, mem->entries, false);
         call_rcu(&mem->rcu, mm_iommu_free);
 }
 
-long mm_iommu_put(struct mm_iommu_table_group_mem_t *mem)
+long mm_iommu_put(struct mm_struct *mm, struct mm_iommu_table_group_mem_t *mem)
 {
         long ret = 0;
 
-        if (!current || !current->mm)
-                return -ESRCH; /* process exited */
-
         mutex_lock(&mem_list_mutex);
 
         if (mem->used == 0) {
@@ -297,6 +287,8 @@ long mm_iommu_put(struct mm_iommu_table_group_mem_t *mem)
         /* @mapped became 0 so now mappings are disabled, release the region */
         mm_iommu_release(mem);
 
+        mm_iommu_adjust_locked_vm(mm, mem->entries, false);
+
 unlock_exit:
         mutex_unlock(&mem_list_mutex);
 
@@ -304,14 +296,12 @@ unlock_exit:
 }
 EXPORT_SYMBOL_GPL(mm_iommu_put);
 
-struct mm_iommu_table_group_mem_t *mm_iommu_lookup(unsigned long ua,
-                unsigned long size)
+struct mm_iommu_table_group_mem_t *mm_iommu_lookup(struct mm_struct *mm,
+                unsigned long ua, unsigned long size)
 {
         struct mm_iommu_table_group_mem_t *mem, *ret = NULL;
 
-        list_for_each_entry_rcu(mem,
-                        &current->mm->context.iommu_group_mem_list,
-                        next) {
+        list_for_each_entry_rcu(mem, &mm->context.iommu_group_mem_list, next) {
                 if ((mem->ua <= ua) &&
                                 (ua + size <= mem->ua +
                                  (mem->entries << PAGE_SHIFT))) {
@@ -324,14 +314,12 @@ struct mm_iommu_table_group_mem_t *mm_iommu_lookup(unsigned long ua,
 }
 EXPORT_SYMBOL_GPL(mm_iommu_lookup);
 
-struct mm_iommu_table_group_mem_t *mm_iommu_find(unsigned long ua,
-                unsigned long entries)
+struct mm_iommu_table_group_mem_t *mm_iommu_find(struct mm_struct *mm,
+                unsigned long ua, unsigned long entries)
 {
         struct mm_iommu_table_group_mem_t *mem, *ret = NULL;
 
-        list_for_each_entry_rcu(mem,
-                        &current->mm->context.iommu_group_mem_list,
-                        next) {
+        list_for_each_entry_rcu(mem, &mm->context.iommu_group_mem_list, next) {
                 if ((mem->ua == ua) && (mem->entries == entries)) {
                         ret = mem;
                         break;