[PATCH] uml: make copy_*_user atomic

Make __copy_*_user_inatomic really atomic to avoid "Sleeping function called in
atomic context" warnings, especially from futex code.

This is made by adding another kmap_atomic slot and making copy_*_user_skas
use kmap_atomic; also copy_*_user() becomes atomic, but that's true and is not
a problem for i386 (and we can always add might_sleep there as done
elsewhere).  For TT mode kmap is not used, so there's no need for this.

I've had to use another slot since both KM_USER0 and KM_USER1 are used
elsewhere and could cause conflicts.  Till now we reused the kmap_atomic slot
list from the subarch, but that's not needed as that list must contain the
common ones (used by generic code) + the ones used in architecture specific
code (and Uml till now used none); so I've taken the i386 one after comparing
it with ones from other archs, and added KM_UML_USERCOPY.

Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Cc: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 9 insertions, 6 deletions

diff --git a/arch/um/kernel/skas/uaccess.c b/arch/um/kernel/skas/uaccess.c
index 5992c3257167..8912cec0fe43 100644
--- a/arch/um/kernel/skas/uaccess.c
+++ b/arch/um/kernel/skas/uaccess.c
@@ -8,6 +8,7 @@
 #include "linux/kernel.h"
 #include "linux/string.h"
 #include "linux/fs.h"
+#include "linux/hardirq.h"
 #include "linux/highmem.h"
 #include "asm/page.h"
 #include "asm/pgtable.h"
@@ -38,7 +39,7 @@ static unsigned long maybe_map(unsigned long virt, int is_write)
         return((unsigned long) phys);
 }
 
-static int do_op(unsigned long addr, int len, int is_write,
+static int do_op_one_page(unsigned long addr, int len, int is_write,
                  int (*op)(unsigned long addr, int len, void *arg), void *arg)
 {
         struct page *page;
@@ -49,9 +50,11 @@ static int do_op(unsigned long addr, int len, int is_write,
                 return(-1);
 
         page = phys_to_page(addr);
-        addr = (unsigned long) kmap(page) + (addr & ~PAGE_MASK);
+        addr = (unsigned long) kmap_atomic(page, KM_UML_USERCOPY) + (addr & ~PAGE_MASK);
+
         n = (*op)(addr, len, arg);
-        kunmap(page);
+
+        kunmap_atomic(page, KM_UML_USERCOPY);
 
         return(n);
 }
@@ -77,7 +80,7 @@ static void do_buffer_op(void *jmpbuf, void *arg_ptr)
         remain = len;
 
         current->thread.fault_catcher = jmpbuf;
-        n = do_op(addr, size, is_write, op, arg);
+        n = do_op_one_page(addr, size, is_write, op, arg);
         if(n != 0){
                 *res = (n < 0 ? remain : 0);
                 goto out;
@@ -91,7 +94,7 @@ static void do_buffer_op(void *jmpbuf, void *arg_ptr)
         }
 
         while(addr < ((addr + remain) & PAGE_MASK)){
-                n = do_op(addr, PAGE_SIZE, is_write, op, arg);
+                n = do_op_one_page(addr, PAGE_SIZE, is_write, op, arg);
                 if(n != 0){
                         *res = (n < 0 ? remain : 0);
                         goto out;
@@ -105,7 +108,7 @@ static void do_buffer_op(void *jmpbuf, void *arg_ptr)
                 goto out;
         }
 
-        n = do_op(addr, remain, is_write, op, arg);
+        n = do_op_one_page(addr, remain, is_write, op, arg);
         if(n != 0)
                 *res = (n < 0 ? remain : 0);
         else *res = 0;