mm: remove more IS_ERR_VALUE abuses

The do_brk() and vm_brk() return value was "unsigned long" and returned
the starting address on success, and an error value on failure.  The
reasons are entirely historical, and go back to it basically behaving
like the mmap() interface does.

However, nobody actually wanted that interface, and it causes totally
pointless IS_ERR_VALUE() confusion.

What every single caller actually wants is just the simpler integer
return of zero for success and negative error number on failure.

So just convert to that much clearer and more common calling convention,
and get rid of all the IS_ERR_VALUE() uses wrt vm_brk().

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 9 insertions, 9 deletions

diff --git a/mm/mmap.c b/mm/mmap.c
index d3d9a94ca031..de2c1769cc68 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -168,7 +168,7 @@ static struct vm_area_struct *remove_vma(struct vm_area_struct *vma)
         return next;
 }
 
-static unsigned long do_brk(unsigned long addr, unsigned long len);
+static int do_brk(unsigned long addr, unsigned long len);
 
 SYSCALL_DEFINE1(brk, unsigned long, brk)
 {
@@ -224,7 +224,7 @@ SYSCALL_DEFINE1(brk, unsigned long, brk)
                 goto out;
 
         /* Ok, looks good - let it rip. */
-        if (do_brk(oldbrk, newbrk-oldbrk) != oldbrk)
+        if (do_brk(oldbrk, newbrk-oldbrk) < 0)
                 goto out;
 
 set_brk:
@@ -2625,7 +2625,7 @@ static inline void verify_mm_writelocked(struct mm_struct *mm)
  *  anonymous maps.  eventually we may be able to do some
  *  brk-specific accounting here.
  */
-static unsigned long do_brk(unsigned long addr, unsigned long len)
+static int do_brk(unsigned long addr, unsigned long len)
 {
         struct mm_struct *mm = current->mm;
         struct vm_area_struct *vma, *prev;
@@ -2636,7 +2636,7 @@ static unsigned long do_brk(unsigned long addr, unsigned long len)
 
         len = PAGE_ALIGN(len);
         if (!len)
-                return addr;
+                return 0;
 
         flags = VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags;
 
@@ -2703,13 +2703,13 @@ out:
         if (flags & VM_LOCKED)
                 mm->locked_vm += (len >> PAGE_SHIFT);
         vma->vm_flags |= VM_SOFTDIRTY;
-        return addr;
+        return 0;
 }
 
-unsigned long vm_brk(unsigned long addr, unsigned long len)
+int vm_brk(unsigned long addr, unsigned long len)
 {
         struct mm_struct *mm = current->mm;
-        unsigned long ret;
+        int ret;
         bool populate;
 
         if (down_write_killable(&mm->mmap_sem))
@@ -2718,7 +2718,7 @@ unsigned long vm_brk(unsigned long addr, unsigned long len)
         ret = do_brk(addr, len);
         populate = ((mm->def_flags & VM_LOCKED) != 0);
         up_write(&mm->mmap_sem);
-        if (populate)
+        if (populate && !ret)
                 mm_populate(addr, len);
         return ret;
 }
diff --git a/mm/nommu.c b/mm/nommu.c
index c8bd59a03c71..c2e58880207f 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -1682,7 +1682,7 @@ void exit_mmap(struct mm_struct *mm)
         }
 }
 
-unsigned long vm_brk(unsigned long addr, unsigned long len)
+int vm_brk(unsigned long addr, unsigned long len)
 {
         return -ENOMEM;
 }