Refactor offwaketime stack id error handling

tools/offcputime.py

@@ -292,7 +292,7 @@ def signal_ignore(signal, frame):
  else:
  line.extend([b.sym(addr, k.tgid) for addr in reversed(user_stack)])
  if not args.user_stacks_only:
- line.extend(["-"] if (need_delimiter and k.kernel_stack_id >= 0) else [])
+ line.extend(["-"] if (need_delimiter and k.kernel_stack_id >= 0 and k.user_stack_id >= 0) else [])
  if stack_id_err(k.kernel_stack_id):
  line.append("[Missed Kernel Stack]")
  else:
@@ -307,7 +307,7 @@ def signal_ignore(signal, frame):
  for addr in kernel_stack:
  print(" %s" % b.ksym(addr))
  if not args.kernel_stacks_only:
- if need_delimiter and k.user_stack_id >= 0:
+ if need_delimiter and k.user_stack_id >= 0 and k.kernel_stack_id >= 0:
  print(" --")
  if stack_id_err(k.user_stack_id):
  print(" [Missed User Stack]")

tools/offwaketime.py

@@ -35,6 +35,11 @@ def positive_nonzero_int(val):
  raise argparse.ArgumentTypeError("must be nonzero")
  return ival
 
+def stack_id_err(stack_id):
+ # -EFAULT in get_stackid normally means the stack-trace is not availible,
+ # Such as getting kernel stack trace in userspace code
+ return (stack_id < 0) and (stack_id != -errno.EFAULT)
+
 # arguments
 examples = """examples:
  ./offwaketime # trace off-CPU + waker stack time until Ctrl-C
@@ -239,9 +244,8 @@ def signal_ignore(signal, frame):
 bpf_text = bpf_text.replace('MAXBLOCK_US_VALUE', str(args.max_block_time))
 
 # handle stack args
-kernel_stack_get = "stack_traces.get_stackid(ctx, BPF_F_REUSE_STACKID)"
-user_stack_get = \
- "stack_traces.get_stackid(ctx, BPF_F_REUSE_STACKID | BPF_F_USER_STACK)"
+kernel_stack_get = "stack_traces.get_stackid(ctx, 0)"
+user_stack_get = "stack_traces.get_stackid(ctx, BPF_F_USER_STACK)"
 stack_context = ""
 if args.user_stacks_only:
  stack_context = "user"
@@ -288,15 +292,20 @@ def signal_ignore(signal, frame):
 has_enomem = False
 counts = b.get_table("counts")
 stack_traces = b.get_table("stack_traces")
+need_delimiter = args.delimited and not (args.kernel_stacks_only or
+ args.user_stacks_only)
 for k, v in sorted(counts.items(), key=lambda counts: counts[1].value):
  # handle get_stackid errors
- # check for an ENOMEM error
- if k.w_k_stack_id == -errno.ENOMEM or \
- k.t_k_stack_id == -errno.ENOMEM or \
- k.w_u_stack_id == -errno.ENOMEM or \
- k.t_u_stack_id == -errno.ENOMEM:
- missing_stacks += 1
- continue
+ if not args.user_stacks_only:
+ missing_stacks += int(stack_id_err(k.w_k_stack_id))
+ missing_stacks += int(stack_id_err(k.t_k_stack_id))
+ has_enomem = has_enomem or (k.w_k_stack_id == -errno.ENOMEM) or \
+ (k.t_k_stack_id == -errno.ENOMEM)
+ if not args.kernel_stacks_only:
+ missing_stacks += int(stack_id_err(k.w_u_stack_id))
+ missing_stacks += int(stack_id_err(k.t_u_stack_id))
+ has_enomem = has_enomem or (k.w_u_stack_id == -errno.ENOMEM) or \
+ (k.t_u_stack_id == -errno.ENOMEM)
 
  waker_user_stack = [] if k.w_u_stack_id < 1 else \
  reversed(list(stack_traces.walk(k.w_u_stack_id))[1:])
@@ -309,47 +318,76 @@ def signal_ignore(signal, frame):
 
  if folded:
  # print folded stack output
- line = \
- [k.target.decode()] + \
- [b.sym(addr, k.t_tgid)
- for addr in reversed(list(target_user_stack)[1:])] + \
- (["-"] if args.delimited else [""]) + \
- [b.ksym(addr)
- for addr in reversed(list(target_kernel_stack)[1:])] + \
- ["--"] + \
- [b.ksym(addr)
- for addr in reversed(list(waker_kernel_stack))] + \
- (["-"] if args.delimited else [""]) + \
- [b.sym(addr, k.w_tgid)
- for addr in reversed(list(waker_user_stack))] + \
- [k.waker.decode()]
+ line = [k.target.decode()]
+ if not args.kernel_stacks_only:
+ if stack_id_err(k.t_u_stack_id):
+ line.append("[Missed User Stack]")
+ else:
+ line.extend([b.sym(addr, k.t_tgid)
+ for addr in reversed(list(target_user_stack)[1:])])
+ if not args.user_stacks_only:
+ line.extend(["-"] if (need_delimiter and k.t_k_stack_id > 0 and k.t_u_stack_id > 0) else [])
+ if stack_id_err(k.t_k_stack_id):
+ line.append("[Missed Kernel Stack]")
+ else:
+ line.extend([b.ksym(addr)
+ for addr in reversed(list(target_kernel_stack)[1:])])
+ line.append("--")
+ if not args.user_stacks_only:
+ if stack_id_err(k.w_k_stack_id):
+ line.append("[Missed Kernel Stack]")
+ else:
+ line.extend([b.ksym(addr)
+ for addr in reversed(list(waker_kernel_stack))])
+ if not args.kernel_stacks_only:
+ line.extend(["-"] if (need_delimiter and k.w_u_stack_id > 0 and k.w_k_stack_id > 0) else [])
+ if stack_id_err(k.w_u_stack_id):
+ line.extend("[Missed User Stack]")
+ else:
+ line.extend([b.sym(addr, k.w_tgid)
+ for addr in reversed(list(waker_user_stack))])
+ line.append(k.waker.decode())
  print("%s %d" % (";".join(line), v.value))
-
  else:
  # print wakeup name then stack in reverse order
  print(" %-16s %s %s" % ("waker:", k.waker.decode(), k.t_pid))
- for addr in waker_user_stack:
- print(" %s" % b.sym(addr, k.w_tgid))
- if args.delimited:
- print(" -")
- for addr in waker_kernel_stack:
- print(" %s" % b.ksym(addr))
+ if not args.kernel_stacks_only:
+ if stack_id_err(k.w_u_stack_id):
+ print(" [Missed User Stack]")
+ else:
+ for addr in waker_user_stack:
+ print(" %s" % b.sym(addr, k.w_tgid))
+ if not args.user_stacks_only:
+ if need_delimiter and k.w_u_stack_id > 0 and k.w_k_stack_id > 0:
+ print(" -")
+ if stack_id_err(k.w_k_stack_id):
+ print(" [Missed Kernel Stack]")
+ else:
+ for addr in waker_kernel_stack:
+ print(" %s" % b.ksym(addr))
 
  # print waker/wakee delimiter
  print(" %-16s %s" % ("--", "--"))
-
- # print default multi-line stack output
- for addr in target_kernel_stack:
- print(" %s" % b.ksym(addr))
- if args.delimited:
- print(" -")
- for addr in target_user_stack:
- print(" %s" % b.sym(addr, k.t_tgid))
+
+ if not args.user_stacks_only:
+ if stack_id_err(k.t_k_stack_id):
+ print(" [Missed Kernel Stack]")
+ else:
+ for addr in target_kernel_stack:
+ print(" %s" % b.ksym(addr))
+ if not args.kernel_stacks_only:
+ if need_delimiter and k.t_u_stack_id > 0 and k.t_k_stack_id > 0:
+ print(" -")
+ if stack_id_err(k.t_u_stack_id):
+ print(" [Missed User Stack]")
+ else:
+ for addr in target_user_stack:
+ print(" %s" % b.sym(addr, k.t_tgid))
  print(" %-16s %s %s" % ("target:", k.target.decode(), k.w_pid))
  print(" %d\n" % v.value)
 
 if missing_stacks > 0:
  enomem_str = " Consider increasing --stack-storage-size."
- print("WARNING: %d stack traces could not be displayed.%s" %
- (missing_stacks, enomem_str),
+ print("WARNING: %d stack traces lost and could not be displayed.%s" %
+ (missing_stacks, (enomem_str if has_enomem else "")),
  file=stderr)