tools/rtla: Improve exception handling in timerlat_load.py

The enhancements made to timerlat_load.py are intended to improve the script's exception handling.

Summary of the changes:
  - Specific exceptions are now caught for CPU affinity and priority
    settings, with clearer error messages provided.
  - The timerlat file descriptor opening now includes handling for
    PermissionError and OSError, with informative messages.
  - In the infinite loop, generic exceptions have been replaced with
    specific types like KeyboardInterrupt and IOError, improving feedback.

 Before:
    $ sudo python timerlat_load.py 122
    Error setting affinity
 After:
    $ sudo python timerlat_load.py 122
    Error setting affinity: [Errno 22] Invalid argument

 Before:
    $ sudo python timerlat_load.py 1 -p 950
    Error setting priority
 After:
    $ sudo python timerlat_load.py 1 -p 950
    Error setting priority: [Errno 22] Invalid argument

 Before:
    $ python timerlat_load.py 1
    Error opening timerlat fd, did you run timerlat -U?
 After:
    $ python timerlat_load.py 1
    Permission denied. Please check your access rights.

Cc: "lgoncalv@redhat.com" <lgoncalv@redhat.com>
Cc: "jkacur@redhat.com" <jkacur@redhat.com>
Link: https://lore.kernel.org/Q_k1s4hBtUy2px8ou0QKenjEK2_T_LoV8IxAE79aBakBogb-7uHp2fpET3oWtI1t3dy8uKjWeRzQOdKNzIzOOpyM4OjutJOriZ9TrGY6b-g=@protonmail.com
Signed-off-by: Furkan Onder <furkanonder@protonmail.com>
Reviewed-by: Tomas Glozar <tglozar@redhat.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

Author: furkanonder

tools/tracing/rtla/sample/timerlat_load.py

@@ -31,43 +31,48 @@
 
 try:
     affinity_mask = {args.cpu}
-except:
-    print("Invalid cpu: " + args.cpu)
-    exit(1)
-
-try:
     os.sched_setaffinity(0, affinity_mask)
-except:
-    print("Error setting affinity")
-    exit(1)
+except Exception as e:
+    print(f"Error setting affinity: {e}")
+    sys.exit(1)
 
 if args.prio:
     try:
         param = os.sched_param(args.prio)
         os.sched_setscheduler(0, os.SCHED_FIFO, param)
-    except:
-        print("Error setting priority")
-        exit(1)
+    except Exception as e:
+        print(f"Error setting priority: {e}")
+        sys.exit(1)
 
 try:
     timerlat_path = f"/sys/kernel/tracing/osnoise/per_cpu/cpu{args.cpu}/timerlat_fd"
     timerlat_fd = open(timerlat_path, 'r')
-except:
+except PermissionError:
+    print("Permission denied. Please check your access rights.")
+    sys.exit(1)
+except OSError:
     print("Error opening timerlat fd, did you run timerlat -U?")
-    exit(1)
+    sys.exit(1)
 
 try:
     data_fd = open("/dev/full", 'r')
-except:
-    print("Error opening data fd")
+except Exception as e:
+    print(f"Error opening data fd: {e}")
+    sys.exit(1)
 
 while True:
     try:
         timerlat_fd.read(1)
         data_fd.read(20 * 1024 * 1024)
-    except:
+    except KeyboardInterrupt:
         print("Leaving")
         break
+    except IOError as e:
+        print(f"I/O error occurred: {e}")
+        break
+    except Exception as e:
+        print(f"Unexpected error: {e}")
+        break
 
 timerlat_fd.close()
 data_fd.close()