---

yaml
---
r: 83631
b: refs/heads/master
c: e33f663
h: refs/heads/master
i:
  83629: e6bef04
  83627: 49d13d5
  83623: f9c4437
  83615: 53b23f9
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 38192d52f159bc06b7f523800c10b583cdd661d5
+refs/heads/master: e33f6635da037ed4d2634ee6bdf5c4d601946c18

trunk/Documentation/BUG-HUNTING

@@ -214,6 +214,23 @@ And recompile the kernel with CONFIG_DEBUG_INFO enabled:
   gdb vmlinux
   (gdb) p vt_ioctl
   (gdb) l *(0x<address of vt_ioctl> + 0xda8)
+or, as one command
+  (gdb) l *(vt_ioctl + 0xda8)
+
+If you have a call trace, such as :-
+>Call Trace:
+> [<ffffffff8802c8e9>] :jbd:log_wait_commit+0xa3/0xf5
+> [<ffffffff810482d9>] autoremove_wake_function+0x0/0x2e
+> [<ffffffff8802770b>] :jbd:journal_stop+0x1be/0x1ee
+> ...
+this shows the problem in the :jbd: module. You can load that module in gdb
+and list the relevant code.
+  gdb fs/jbd/jbd.ko
+  (gdb) p log_wait_commit
+  (gdb) l *(0x<address> + 0xa3)
+or
+  (gdb) l *(log_wait_commit + 0xa3)
+
 
 Another very useful option of the Kernel Hacking section in menuconfig is
 Debug memory allocations. This will help you see whether data has been

trunk/Documentation/DocBook/kernel-locking.tmpl

@@ -717,15 +717,15 @@ used, and when it gets full, throws out the least used one.
     <para>
 For our first example, we assume that all operations are in user
 context (ie. from system calls), so we can sleep.  This means we can
-use a semaphore to protect the cache and all the objects within
+use a mutex to protect the cache and all the objects within
 it.  Here's the code:
     </para>
 
     <programlisting>
 #include &lt;linux/list.h&gt;
 #include &lt;linux/slab.h&gt;
 #include &lt;linux/string.h&gt;
-#include &lt;asm/semaphore.h&gt;
+#include &lt;linux/mutex.h&gt;
 #include &lt;asm/errno.h&gt;
 
 struct object
@@ -737,7 +737,7 @@ struct object
 };
 
 /* Protects the cache, cache_num, and the objects within it */
-static DECLARE_MUTEX(cache_lock);
+static DEFINE_MUTEX(cache_lock);
 static LIST_HEAD(cache);
 static unsigned int cache_num = 0;
 #define MAX_CACHE_SIZE 10
@@ -789,31 +789,31 @@ int cache_add(int id, const char *name)
         obj-&gt;id = id;
         obj-&gt;popularity = 0;
 
-        down(&amp;cache_lock);
+        mutex_lock(&amp;cache_lock);
         __cache_add(obj);
-        up(&amp;cache_lock);
+        mutex_unlock(&amp;cache_lock);
         return 0;
 }
 
 void cache_delete(int id)
 {
-        down(&amp;cache_lock);
+        mutex_lock(&amp;cache_lock);
         __cache_delete(__cache_find(id));
-        up(&amp;cache_lock);
+        mutex_unlock(&amp;cache_lock);
 }
 
 int cache_find(int id, char *name)
 {
         struct object *obj;
         int ret = -ENOENT;
 
-        down(&amp;cache_lock);
+        mutex_lock(&amp;cache_lock);
         obj = __cache_find(id);
         if (obj) {
                 ret = 0;
                 strcpy(name, obj-&gt;name);
         }
-        up(&amp;cache_lock);
+        mutex_unlock(&amp;cache_lock);
         return ret;
 }
 </programlisting>
@@ -853,7 +853,7 @@ The change is shown below, in standard patch format: the
          int popularity;
  };
 
--static DECLARE_MUTEX(cache_lock);
+-static DEFINE_MUTEX(cache_lock);
 +static spinlock_t cache_lock = SPIN_LOCK_UNLOCKED;
  static LIST_HEAD(cache);
  static unsigned int cache_num = 0;
@@ -870,22 +870,22 @@ The change is shown below, in standard patch format: the
          obj-&gt;id = id;
          obj-&gt;popularity = 0;
 
--        down(&amp;cache_lock);
+-        mutex_lock(&amp;cache_lock);
 +        spin_lock_irqsave(&amp;cache_lock, flags);
          __cache_add(obj);
--        up(&amp;cache_lock);
+-        mutex_unlock(&amp;cache_lock);
 +        spin_unlock_irqrestore(&amp;cache_lock, flags);
          return 0;
  }
 
  void cache_delete(int id)
  {
--        down(&amp;cache_lock);
+-        mutex_lock(&amp;cache_lock);
 +        unsigned long flags;
 +
 +        spin_lock_irqsave(&amp;cache_lock, flags);
          __cache_delete(__cache_find(id));
--        up(&amp;cache_lock);
+-        mutex_unlock(&amp;cache_lock);
 +        spin_unlock_irqrestore(&amp;cache_lock, flags);
  }
 
@@ -895,14 +895,14 @@ The change is shown below, in standard patch format: the
          int ret = -ENOENT;
 +        unsigned long flags;
 
--        down(&amp;cache_lock);
+-        mutex_lock(&amp;cache_lock);
 +        spin_lock_irqsave(&amp;cache_lock, flags);
          obj = __cache_find(id);
          if (obj) {
                  ret = 0;
                  strcpy(name, obj-&gt;name);
          }
--        up(&amp;cache_lock);
+-        mutex_unlock(&amp;cache_lock);
 +        spin_unlock_irqrestore(&amp;cache_lock, flags);
          return ret;
  }

trunk/Documentation/fb/deferred_io.txt

@@ -7,10 +7,10 @@ IO. The following example may be a useful explanation of how one such setup
 works:
 
 - userspace app like Xfbdev mmaps framebuffer
-- deferred IO and driver sets up nopage and page_mkwrite handlers
+- deferred IO and driver sets up fault and page_mkwrite handlers
 - userspace app tries to write to mmaped vaddress
-- we get pagefault and reach nopage handler
-- nopage handler finds and returns physical page
+- we get pagefault and reach fault handler
+- fault handler finds and returns physical page
 - we get page_mkwrite where we add this page to a list
 - schedule a workqueue task to be run after a delay
 - app continues writing to that page with no additional cost. this is

trunk/Documentation/feature-removal-schedule.txt

@@ -208,13 +208,6 @@ Who:	Randy Dunlap <randy.dunlap@oracle.com>
 
 ---------------------------
 
-What:  drivers depending on OSS_OBSOLETE
-When:  options in 2.6.23, code in 2.6.25
-Why:   obsolete OSS drivers
-Who:   Adrian Bunk <bunk@stusta.de>
-
----------------------------
-
 What: libata spindown skipping and warning
 When: Dec 2008
 Why:  Some halt(8) implementations synchronize caches for and spin

trunk/Documentation/filesystems/proc.txt

@@ -1029,6 +1029,14 @@ nr_inodes
 Denotes the  number  of  inodes the system has allocated. This number will
 grow and shrink dynamically.
 
+nr_open
+-------
+
+Denotes the maximum number of file-handles a process can
+allocate. Default value is 1024*1024 (1048576) which should be
+enough for most machines. Actual limit depends on RLIMIT_NOFILE
+resource limit.
+
 nr_free_inodes
 --------------
 

trunk/Documentation/kprobes.txt

@@ -96,7 +96,9 @@ or in registers (e.g., for x86_64 or for an i386 fastcall function).
 The jprobe will work in either case, so long as the handler's
 prototype matches that of the probed function.
 
-1.3 How Does a Return Probe Work?
+1.3 Return Probes
+
+1.3.1 How Does a Return Probe Work?
 
 When you call register_kretprobe(), Kprobes establishes a kprobe at
 the entry to the function.  When the probed function is called and this
@@ -107,9 +109,9 @@ At boot time, Kprobes registers a kprobe at the trampoline.
 
 When the probed function executes its return instruction, control
 passes to the trampoline and that probe is hit.  Kprobes' trampoline
-handler calls the user-specified handler associated with the kretprobe,
-then sets the saved instruction pointer to the saved return address,
-and that's where execution resumes upon return from the trap.
+handler calls the user-specified return handler associated with the
+kretprobe, then sets the saved instruction pointer to the saved return
+address, and that's where execution resumes upon return from the trap.
 
 While the probed function is executing, its return address is
 stored in an object of type kretprobe_instance.  Before calling
@@ -131,6 +133,30 @@ zero when the return probe is registered, and is incremented every
 time the probed function is entered but there is no kretprobe_instance
 object available for establishing the return probe.
 
+1.3.2 Kretprobe entry-handler
+
+Kretprobes also provides an optional user-specified handler which runs
+on function entry. This handler is specified by setting the entry_handler
+field of the kretprobe struct. Whenever the kprobe placed by kretprobe at the
+function entry is hit, the user-defined entry_handler, if any, is invoked.
+If the entry_handler returns 0 (success) then a corresponding return handler
+is guaranteed to be called upon function return. If the entry_handler
+returns a non-zero error then Kprobes leaves the return address as is, and
+the kretprobe has no further effect for that particular function instance.
+
+Multiple entry and return handler invocations are matched using the unique
+kretprobe_instance object associated with them. Additionally, a user
+may also specify per return-instance private data to be part of each
+kretprobe_instance object. This is especially useful when sharing private
+data between corresponding user entry and return handlers. The size of each
+private data object can be specified at kretprobe registration time by
+setting the data_size field of the kretprobe struct. This data can be
+accessed through the data field of each kretprobe_instance object.
+
+In case probed function is entered but there is no kretprobe_instance
+object available, then in addition to incrementing the nmissed count,
+the user entry_handler invocation is also skipped.
+
 2. Architectures Supported
 
 Kprobes, jprobes, and return probes are implemented on the following
@@ -274,6 +300,8 @@ of interest:
 - ret_addr: the return address
 - rp: points to the corresponding kretprobe object
 - task: points to the corresponding task struct
+- data: points to per return-instance private data; see "Kretprobe
+	entry-handler" for details.
 
 The regs_return_value(regs) macro provides a simple abstraction to
 extract the return value from the appropriate register as defined by
@@ -556,23 +584,52 @@ report failed calls to sys_open().
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/kprobes.h>
+#include <linux/ktime.h>
+
+/* per-instance private data */
+struct my_data {
+	ktime_t entry_stamp;
+};
 
 static const char *probed_func = "sys_open";
 
-/* Return-probe handler: If the probed function fails, log the return value. */
-static int ret_handler(struct kretprobe_instance *ri, struct pt_regs *regs)
+/* Timestamp function entry. */
+static int entry_handler(struct kretprobe_instance *ri, struct pt_regs *regs)
+{
+	struct my_data *data;
+
+	if(!current->mm)
+		return 1; /* skip kernel threads */
+
+	data = (struct my_data *)ri->data;
+	data->entry_stamp = ktime_get();
+	return 0;
+}
+
+/* If the probed function failed, log the return value and duration.
+ * Duration may turn out to be zero consistently, depending upon the
+ * granularity of time accounting on the platform. */
+static int return_handler(struct kretprobe_instance *ri, struct pt_regs *regs)
 {
 	int retval = regs_return_value(regs);
+	struct my_data *data = (struct my_data *)ri->data;
+	s64 delta;
+	ktime_t now;
+
 	if (retval < 0) {
-		printk("%s returns %d\n", probed_func, retval);
+		now = ktime_get();
+		delta = ktime_to_ns(ktime_sub(now, data->entry_stamp));
+		printk("%s: return val = %d (duration = %lld ns)\n",
+		       probed_func, retval, delta);
 	}
 	return 0;
 }
 
 static struct kretprobe my_kretprobe = {
-	.handler = ret_handler,
-	/* Probe up to 20 instances concurrently. */
-	.maxactive = 20
+	.handler = return_handler,
+	.entry_handler = entry_handler,
+	.data_size = sizeof(struct my_data),
+	.maxactive = 20, /* probe up to 20 instances concurrently */
 };
 
 static int __init kretprobe_init(void)
@@ -584,7 +641,7 @@ static int __init kretprobe_init(void)
 		printk("register_kretprobe failed, returned %d\n", ret);
 		return -1;
 	}
-	printk("Planted return probe at %p\n", my_kretprobe.kp.addr);
+	printk("Kretprobe active on %s\n", my_kretprobe.kp.symbol_name);
 	return 0;
 }
 
@@ -594,7 +651,7 @@ static void __exit kretprobe_exit(void)
 	printk("kretprobe unregistered\n");
 	/* nmissed > 0 suggests that maxactive was set too low. */
 	printk("Missed probing %d instances of %s\n",
-		my_kretprobe.nmissed, probed_func);
+	       my_kretprobe.nmissed, probed_func);
 }
 
 module_init(kretprobe_init)

trunk/Documentation/kref.txt

@@ -141,10 +141,10 @@ The last rule (rule 3) is the nastiest one to handle.  Say, for
 instance, you have a list of items that are each kref-ed, and you wish
 to get the first one.  You can't just pull the first item off the list
 and kref_get() it.  That violates rule 3 because you are not already
-holding a valid pointer.  You must add locks or semaphores.  For
-instance:
+holding a valid pointer.  You must add a mutex (or some other lock).
+For instance:
 
-static DECLARE_MUTEX(sem);
+static DEFINE_MUTEX(mutex);
 static LIST_HEAD(q);
 struct my_data
 {
@@ -155,12 +155,12 @@ struct my_data
 static struct my_data *get_entry()
 {
 	struct my_data *entry = NULL;
-	down(&sem);
+	mutex_lock(&mutex);
 	if (!list_empty(&q)) {
 		entry = container_of(q.next, struct my_q_entry, link);
 		kref_get(&entry->refcount);
 	}
-	up(&sem);
+	mutex_unlock(&mutex);
 	return entry;
 }
 
@@ -174,9 +174,9 @@ static void release_entry(struct kref *ref)
 
 static void put_entry(struct my_data *entry)
 {
-	down(&sem);
+	mutex_lock(&mutex);
 	kref_put(&entry->refcount, release_entry);
-	up(&sem);
+	mutex_unlock(&mutex);
 }
 
 The kref_put() return value is useful if you do not want to hold the
@@ -191,13 +191,13 @@ static void release_entry(struct kref *ref)
 
 static void put_entry(struct my_data *entry)
 {
-	down(&sem);
+	mutex_lock(&mutex);
 	if (kref_put(&entry->refcount, release_entry)) {
 		list_del(&entry->link);
-		up(&sem);
+		mutex_unlock(&mutex);
 		kfree(entry);
 	} else
-		up(&sem);
+		mutex_unlock(&mutex);
 }
 
 This is really more useful if you have to call other routines as part