drm/msm: dpu: Don't use power_event for vbif_init_memtypes

[sfrench/cifs-2.6.git] / kernel / utsname_sysctl.c

diff --git a/kernel/utsname_sysctl.c b/kernel/utsname_sysctl.c
index 233cd8fc691082363d6c324f1555aa1dd1f33c21..258033d62cb3a4ae8da270df003bb8444f409eeb 100644 (file)
--- a/kernel/utsname_sysctl.c
+++ b/kernel/utsname_sysctl.c
@@ -18,7 +18,7 @@
 
 #ifdef CONFIG_PROC_SYSCTL
 
-static void *get_uts(struct ctl_table *table, int write)
+static void *get_uts(struct ctl_table *table)
 {
        char *which = table->data;
        struct uts_namespace *uts_ns;
@@ -26,21 +26,9 @@ static void *get_uts(struct ctl_table *table, int write)
        uts_ns = current->nsproxy->uts_ns;
        which = (which - (char *)&init_uts_ns) + (char *)uts_ns;
 
-       if (!write)
-               down_read(&uts_sem);
-       else
-               down_write(&uts_sem);
        return which;
 }
 
-static void put_uts(struct ctl_table *table, int write, void *which)
-{
-       if (!write)
-               up_read(&uts_sem);
-       else
-               up_write(&uts_sem);
-}
-
 /*
  *     Special case of dostring for the UTS structure. This has locks
  *     to observe. Should this be in kernel/sys.c ????
@@ -50,13 +38,34 @@ static int proc_do_uts_string(struct ctl_table *table, int write,
 {
        struct ctl_table uts_table;
        int r;
+       char tmp_data[__NEW_UTS_LEN + 1];
+
        memcpy(&uts_table, table, sizeof(uts_table));
-       uts_table.data = get_uts(table, write);
+       uts_table.data = tmp_data;
+
+       /*
+        * Buffer the value in tmp_data so that proc_dostring() can be called
+        * without holding any locks.
+        * We also need to read the original value in the write==1 case to
+        * support partial writes.
+        */
+       down_read(&uts_sem);
+       memcpy(tmp_data, get_uts(table), sizeof(tmp_data));
+       up_read(&uts_sem);
        r = proc_dostring(&uts_table, write, buffer, lenp, ppos);
-       put_uts(table, write, uts_table.data);
 
-       if (write)
+       if (write) {
+               /*
+                * Write back the new value.
+                * Note that, since we dropped uts_sem, the result can
+                * theoretically be incorrect if there are two parallel writes
+                * at non-zero offsets to the same sysctl.
+                */
+               down_write(&uts_sem);
+               memcpy(get_uts(table), tmp_data, sizeof(tmp_data));
+               up_write(&uts_sem);
                proc_sys_poll_notify(table->poll);
+       }
 
        return r;
 }