Replace mutex with spinlock for tracepoint registration (#2882)

Author: aviraxp

kernel/sucompat.c

@@ -13,6 +13,7 @@
 #include <linux/types.h>
 #include <linux/uaccess.h>
 #include <linux/version.h>
+#include <linux/spinlock.h>
 #include <linux/sched/task_stack.h>
 #include <asm/syscall.h>
 #include <trace/events/syscalls.h>
@@ -335,11 +336,12 @@ static struct kprobe *pts_kp = NULL;
 #ifdef CONFIG_KRETPROBES
 
 static int tracepoint_reg_count = 0;
-static DEFINE_MUTEX(tracepoint_reg_mutex);
+static DEFINE_SPINLOCK(tracepoint_reg_lock);
 
 static int syscall_regfunc_handler(struct kretprobe_instance *ri, struct pt_regs *regs)
 {
-    mutex_lock(&tracepoint_reg_mutex);
+    unsigned long flags;
+    spin_lock_irqsave(&tracepoint_reg_lock, flags);
     if (tracepoint_reg_count < 1) {
         // while install our tracepoint, mark our processes
         unmark_all_process();
@@ -349,13 +351,14 @@ static int syscall_regfunc_handler(struct kretprobe_instance *ri, struct pt_regs
         mark_all_process();
     }
     tracepoint_reg_count++;
-    mutex_unlock(&tracepoint_reg_mutex);
+    spin_unlock_irqrestore(&tracepoint_reg_lock, flags);
     return 0;
 }
 
 static int syscall_unregfunc_handler(struct kretprobe_instance *ri, struct pt_regs *regs)
 {
-    mutex_lock(&tracepoint_reg_mutex);
+    unsigned long flags;
+    spin_lock_irqsave(&tracepoint_reg_lock, flags);
     if (tracepoint_reg_count <= 1) {
         // while uninstall our tracepoint, unmark all processes
         unmark_all_process();
@@ -365,7 +368,7 @@ static int syscall_unregfunc_handler(struct kretprobe_instance *ri, struct pt_re
         ksu_mark_running_process();
     }
     tracepoint_reg_count--;
-    mutex_unlock(&tracepoint_reg_mutex);
+    spin_unlock_irqrestore(&tracepoint_reg_lock, flags);
     return 0;
 }