Re: [PATCH] scripts/gdb: fix 'lx-timerlist' on newer kernel

[Jan Kiszka]

On 02.01.23 08:43, Lin Ma wrote:
> After commit 511885d7061e ("lib/timerqueue: Rely on rbtree semantics for
> next timer"), the struct timerqueue_head changes internal field hence
> causes the old lx-timerlist command keeps reporting errors.
> 
> This fix addes a simple version comparison and necessary code for

typo: "adds"

> traversing timerqueue on a newer kernel. Moreover, it fixes some
> python 3.X compatibility bugs.

The gdb scripts are in lock-step with the kernel version they can
inspect. So just move the logic to the current kernel and drop support
for older versions.

Jan

> 
> Test with python 2.7 and python 3.6
> Test with 
> * commit 442284a89a65 ("scripts/gdb: add a timer list command") and 
> * commit 88603b6dc419 ("Linux 6.2-rc2") kernel
> 
> Signed-off-by: Lin Ma <linma@xxxxxxxxxx>
> ---
>  scripts/gdb/linux/timerlist.py | 41 ++++++++++++++++++++++------------
>  1 file changed, 27 insertions(+), 14 deletions(-)
> 
> diff --git a/scripts/gdb/linux/timerlist.py b/scripts/gdb/linux/timerlist.py
> index 071d0dd5a634..65d035df253d 100644
> --- a/scripts/gdb/linux/timerlist.py
> +++ b/scripts/gdb/linux/timerlist.py
> @@ -4,6 +4,7 @@
>  
>  import binascii
>  import gdb
> +import re
>  
>  from linux import constants
>  from linux import cpus
> @@ -42,9 +43,15 @@ def print_timer(rb_node, idx):
>      return text
>  
>  
> -def print_active_timers(base):
> -    curr = base['active']['next']['node']
> -    curr = curr.address.cast(rbtree.rb_node_type.get_type().pointer())
> +def print_active_timers(base, oldver):
> +    # 511885d7061e ("lib/timerqueue: Rely on rbtree semantics for next timer")
> +    if oldver:
> +        curr = base['active']['next']['node']
> +        curr = curr.address.cast(rbtree.rb_node_type.get_type().pointer())
> +    else:
> +        leftmost = base['active']['rb_root']['rb_leftmost']
> +        curr = leftmost.cast(rbtree.rb_node_type.get_type().pointer())
> +
>      idx = 0
>      while curr:
>          yield print_timer(curr, idx)
> @@ -52,7 +59,7 @@ def print_active_timers(base):
>          idx += 1
>  
>  
> -def print_base(base):
> +def print_base(base, oldver):
>      text = " .base:       {}\n".format(base.address)
>      text += " .index:      {}\n".format(base['index'])
>  
> @@ -62,21 +69,20 @@ def print_base(base):
>      if constants.LX_CONFIG_HIGH_RES_TIMERS:
>          text += "  .offset:     {} nsecs\n".format(base['offset'])
>      text += "active timers:\n"
> -    text += "".join([x for x in print_active_timers(base)])
> +    text += "".join([x for x in print_active_timers(base, oldver)])
>      return text
>  
>  
> -def print_cpu(hrtimer_bases, cpu, max_clock_bases):
> +def print_cpu(hrtimer_bases, cpu, max_clock_bases, oldver):
>      cpu_base = cpus.per_cpu(hrtimer_bases, cpu)
>      jiffies = gdb.parse_and_eval("jiffies_64")
>      tick_sched_ptr = gdb.parse_and_eval("&tick_cpu_sched")
>      ts = cpus.per_cpu(tick_sched_ptr, cpu)
>  
>      text = "cpu: {}\n".format(cpu)
> -    for i in xrange(max_clock_bases):
> +    for i in range(max_clock_bases):
>          text += " clock {}:\n".format(i)
> -        text += print_base(cpu_base['clock_base'][i])
> -
> +        text += print_base(cpu_base['clock_base'][i], oldver)
>          if constants.LX_CONFIG_HIGH_RES_TIMERS:
>              fmts = [("  .{}   : {} nsecs", 'expires_next'),
>                      ("  .{}    : {}", 'hres_active'),
> @@ -165,7 +171,7 @@ def pr_cpumask(mask):
>          i -= 1
>          start = i * 2
>          end = start + 2
> -        chunks.append(buf[start:end])
> +        chunks.append(str(buf[start:end]))
>          if i != 0 and i % 4 == 0:
>              chunks.append(',')
>  
> @@ -184,14 +190,21 @@ class LxTimerList(gdb.Command):
>  
>      def invoke(self, arg, from_tty):
>          hrtimer_bases = gdb.parse_and_eval("&hrtimer_bases")
> -        max_clock_bases = gdb.parse_and_eval("HRTIMER_MAX_CLOCK_BASES")
> -
> -        text = "Timer List Version: gdb scripts\n"
> +        max_clock_bases = gdb.parse_and_eval("(int)HRTIMER_MAX_CLOCK_BASES")
> +        banner = gdb.parse_and_eval("(char *)linux_banner").string()
> +        r = re.match(r"^Linux version (.+) \(.*@.*$", banner)
> +        if not r:
> +            gdb.write("failed to load image version")
> +            return
> +        lver = r.group(1)
> +        oldver = lver < '5.3.0-rc1'
> +
> +        text = "Timer List Version: gdb scripts, old version: {}\n".format(oldver)
>          text += "HRTIMER_MAX_CLOCK_BASES: {}\n".format(max_clock_bases)
>          text += "now at {} nsecs\n".format(ktime_get())
>  
>          for cpu in cpus.each_online_cpu():
> -            text += print_cpu(hrtimer_bases, cpu, max_clock_bases)
> +            text += print_cpu(hrtimer_bases, cpu, max_clock_bases, oldver)
>  
>          if constants.LX_CONFIG_GENERIC_CLOCKEVENTS:
>              if constants.LX_CONFIG_GENERIC_CLOCKEVENTS_BROADCAST:

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