[PATCH] files: fix preemption issues

With the new fdtable locking rules, you have to protect fdtable with either
->file_lock or rcu_read_lock/unlock().  There are some places where we
aren't doing either.  This patch fixes those places.

Signed-off-by: Dipankar Sarma <dipankar@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

2 files changed, 8 insertions, 2 deletions

diff --git a/arch/alpha/kernel/osf_sys.c b/arch/alpha/kernel/osf_sys.c
index 0636116210d2..01fe990d3e54 100644
--- a/arch/alpha/kernel/osf_sys.c
+++ b/arch/alpha/kernel/osf_sys.c
@@ -37,6 +37,7 @@
 #include <linux/namei.h>
 #include <linux/uio.h>
 #include <linux/vfs.h>
+#include <linux/rcupdate.h>
 
 #include <asm/fpu.h>
 #include <asm/io.h>
@@ -975,6 +976,7 @@ osf_select(int n, fd_set __user *inp, fd_set __user *outp, fd_set __user *exp,
         long timeout;
         int ret = -EINVAL;
         struct fdtable *fdt;
+        int max_fdset;
 
         timeout = MAX_SCHEDULE_TIMEOUT;
         if (tvp) {
@@ -996,8 +998,11 @@ osf_select(int n, fd_set __user *inp, fd_set __user *outp, fd_set __user *exp,
                 }
         }
 
+        rcu_read_lock();
         fdt = files_fdtable(current->files);
-        if (n < 0 || n > fdt->max_fdset)
+        max_fdset = fdt->max_fdset;
+        rcu_read_unlock();
+        if (n < 0 || n > max_fdset)
                 goto out_nofds;
 
         /*
diff --git a/arch/ia64/kernel/perfmon.c b/arch/ia64/kernel/perfmon.c
index af42cda6be80..d71731ee5b61 100644
--- a/arch/ia64/kernel/perfmon.c
+++ b/arch/ia64/kernel/perfmon.c
@@ -2218,12 +2218,13 @@ static void
 pfm_free_fd(int fd, struct file *file)
 {
         struct files_struct *files = current->files;
-        struct fdtable *fdt = files_fdtable(files);
+        struct fdtable *fdt;
 
         /* 
          * there ie no fd_uninstall(), so we do it here
          */
         spin_lock(&files->file_lock);
+        fdt = files_fdtable(files);
         rcu_assign_pointer(fdt->fd[fd], NULL);
         spin_unlock(&files->file_lock);