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@mhiramat.roam.corp.google.com
Cc: Florent Revest <revest@chromium.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Stable-dep-of: 700b2b439766 ("fprobe: Fix to ensure the number of active retprobes is not zero")
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/include/linux/fprobe.h b/include/linux/fprobe.h
index e0d4e61..678f741 100644 (file)
--- 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 be28d1b..441a373 100644 (file)
--- 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;