Patch "fprobe: Add nr_maxactive to specify rethook_node pool size" has been added to the 6.1-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    fprobe: Add nr_maxactive to specify rethook_node pool size

to the 6.1-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     fprobe-add-nr_maxactive-to-specify-rethook_node-pool.patch
and it can be found in the queue-6.1 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 3ebd760fab1840ff832f63608a1d2909713f3b6c
Author: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>
Date:   Thu Feb 2 00:56:19 2023 +0900

    fprobe: Add nr_maxactive to specify rethook_node pool size
    
    [ Upstream commit 59a7a298565aa0ce44ce8e4fbcbb89a19730013a ]
    
    Add nr_maxactive to specify rethook_node pool size. This means
    the maximum number of actively running target functions concurrently
    for probing by exit_handler. Note that if the running function is
    preempted or sleep, it is still counted as 'active'.
    
    Link: https://lkml.kernel.org/r/167526697917.433354.17779774988245113106.stgit@xxxxxxxxxxxxxxxxxxxxxxxxxxxxx
    
    Cc: Florent Revest <revest@xxxxxxxxxxxx>
    Cc: Mark Rutland <mark.rutland@xxxxxxx>
    Cc: Will Deacon <will@xxxxxxxxxx>
    Signed-off-by: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>
    Signed-off-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
    Stable-dep-of: 700b2b439766 ("fprobe: Fix to ensure the number of active retprobes is not zero")
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/include/linux/fprobe.h b/include/linux/fprobe.h
index e0d4e61362491..678f741a7b330 100644
--- a/include/linux/fprobe.h
+++ b/include/linux/fprobe.h
@@ -14,6 +14,7 @@
  * @flags: The status flag.
  * @rethook: The rethook data structure. (internal data)
  * @entry_data_size: The private data storage size.
+ * @nr_maxactive: The max number of active functions.
  * @entry_handler: The callback function for function entry.
  * @exit_handler: The callback function for function exit.
  */
@@ -31,6 +32,7 @@ struct fprobe {
 	unsigned int		flags;
 	struct rethook		*rethook;
 	size_t			entry_data_size;
+	int			nr_maxactive;
 
 	void (*entry_handler)(struct fprobe *fp, unsigned long entry_ip,
 			      struct pt_regs *regs, void *entry_data);
diff --git a/kernel/trace/fprobe.c b/kernel/trace/fprobe.c
index be28d1bc84e80..441a373079213 100644
--- a/kernel/trace/fprobe.c
+++ b/kernel/trace/fprobe.c
@@ -143,7 +143,10 @@ static int fprobe_init_rethook(struct fprobe *fp, int num)
 	}
 
 	/* Initialize rethook if needed */
-	size = num * num_possible_cpus() * 2;
+	if (fp->nr_maxactive)
+		size = fp->nr_maxactive;
+	else
+		size = num * num_possible_cpus() * 2;
 	if (size < 0)
 		return -E2BIG;