[PATCH 0/2][next] update gdb scripts for lockless printk ringbuffer

[PATCH 0/2][next] update gdb scripts for lockless printk ringbuffer

[John Ogness]

Hi,

When we brought in the new lockless printk ringbuffer, we overlooked the gdb
scripts. Here are a set of patches to implement gdb support for the new
ringbuffer.

John Ogness (2):
  scripts/gdb: add utils.read_ulong()
  scripts/gdb: update for lockless printk ringbuffer

 Documentation/admin-guide/kdump/gdbmacros.txt | 153 ++++++++++++------
 scripts/gdb/linux/dmesg.py                    | 139 +++++++++++-----
 scripts/gdb/linux/utils.py                    |   7 +
 3 files changed, 216 insertions(+), 83 deletions(-)

-- 
2.20.1

[PATCH 1/2][next] scripts/gdb: add utils.read_ulong()

[John Ogness]

Add a function for reading unsigned long values, which vary in size
depending on the architecture.

Signed-off-by: John Ogness <john.ogness@linutronix.de>
---

 based on next-20200814

 scripts/gdb/linux/utils.py | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/scripts/gdb/linux/utils.py b/scripts/gdb/linux/utils.py
index ea94221dbd39..ff7c1799d588 100644
--- a/scripts/gdb/linux/utils.py
+++ b/scripts/gdb/linux/utils.py
@@ -123,6 +123,13 @@ def read_u64(buffer, offset):
         return read_u32(buffer, offset + 4) + (read_u32(buffer, offset) << 32)
 
 
+def read_ulong(buffer, offset):
+    if get_long_type().sizeof == 8:
+        return read_u64(buffer, offset)
+    else:
+        return read_u32(buffer, offset)
+
+
 target_arch = None
 
 
-- 
2.20.1

[PATCH 2/2][next] scripts/gdb: update for lockless printk ringbuffer

[John Ogness]

With the introduction of the lockless printk ringbuffer, the data
structure for the kernel log buffer was changed. Update the gdb
scripts to be able to parse/print the new log buffer structure.

Fixes: ("printk: use the lockless ringbuffer")
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reported-by: Nick Desaulniers <ndesaulniers@google.com>
---

 based on next-20200814

 Documentation/admin-guide/kdump/gdbmacros.txt | 153 ++++++++++++------
 scripts/gdb/linux/dmesg.py                    | 139 +++++++++++-----
 2 files changed, 209 insertions(+), 83 deletions(-)

diff --git a/Documentation/admin-guide/kdump/gdbmacros.txt b/Documentation/admin-guide/kdump/gdbmacros.txt
index 220d0a80ca2c..6025534c6c14 100644
--- a/Documentation/admin-guide/kdump/gdbmacros.txt
+++ b/Documentation/admin-guide/kdump/gdbmacros.txt
@@ -170,57 +170,111 @@ document trapinfo
 	address the kernel panicked.
 end
 
-define dump_log_idx
-	set $idx = $arg0
+define dump_record
+	set var $desc = $arg0
 	if ($argc > 1)
-		set $prev_flags = $arg1
+		set var $prev_flags = $arg1
 	else
-		set $prev_flags = 0
+		set var $prev_flags = 0
 	end
-	set $msg = ((struct printk_log *) (log_buf + $idx))
-	set $prefix = 1
-	set $newline = 1
-	set $log = log_buf + $idx + sizeof(*$msg)
-
-	# prev & LOG_CONT && !(msg->flags & LOG_PREIX)
-	if (($prev_flags & 8) && !($msg->flags & 4))
-		set $prefix = 0
+
+	set var $info = &$desc->info
+	set var $prefix = 1
+	set var $newline = 1
+
+	set var $begin = $desc->text_blk_lpos.begin % (1U << prb->text_data_ring.size_bits)
+	set var $next = $desc->text_blk_lpos.next % (1U << prb->text_data_ring.size_bits)
+
+	# handle data-less record
+	if ($begin & 1)
+		set var $text_len = 0
+		set var $log = ""
+	else
+		# handle wrapping data block
+		if ($begin > $next)
+			set var $begin = 0
+		end
+
+		# skip over descriptor id
+		set var $begin = $begin + sizeof(long)
+
+		# handle truncated message
+		if ($next - $begin < $info->text_len)
+			set var $text_len = $next - $begin
+		else
+			set var $text_len = $info->text_len
+		end
+
+		set var $log = &prb->text_data_ring.data[$begin]
+	end
+
+	# prev & LOG_CONT && !(info->flags & LOG_PREIX)
+	if (($prev_flags & 8) && !($info->flags & 4))
+		set var $prefix = 0
 	end
 
-	# msg->flags & LOG_CONT
-	if ($msg->flags & 8)
+	# info->flags & LOG_CONT
+	if ($info->flags & 8)
 		# (prev & LOG_CONT && !(prev & LOG_NEWLINE))
 		if (($prev_flags & 8) && !($prev_flags & 2))
-			set $prefix = 0
+			set var $prefix = 0
 		end
-		# (!(msg->flags & LOG_NEWLINE))
-		if (!($msg->flags & 2))
-			set $newline = 0
+		# (!(info->flags & LOG_NEWLINE))
+		if (!($info->flags & 2))
+			set var $newline = 0
 		end
 	end
 
 	if ($prefix)
-		printf "[%5lu.%06lu] ", $msg->ts_nsec / 1000000000, $msg->ts_nsec % 1000000000
+		printf "[%5lu.%06lu] ", $info->ts_nsec / 1000000000, $info->ts_nsec % 1000000000
 	end
-	if ($msg->text_len != 0)
-		eval "printf \"%%%d.%ds\", $log", $msg->text_len, $msg->text_len
+	if ($text_len)
+		eval "printf \"%%%d.%ds\", $log", $text_len, $text_len
 	end
 	if ($newline)
 		printf "\n"
 	end
-	if ($msg->dict_len > 0)
-		set $dict = $log + $msg->text_len
-		set $idx = 0
-		set $line = 1
-		while ($idx < $msg->dict_len)
+
+	# handle dictionary data
+
+	set var $begin = $desc->dict_blk_lpos.begin % (1U << prb->dict_data_ring.size_bits)
+	set var $next = $desc->dict_blk_lpos.next % (1U << prb->dict_data_ring.size_bits)
+
+	# handle data-less record
+	if ($begin & 1)
+		set var $dict_len = 0
+		set var $dict = ""
+	else
+		# handle wrapping data block
+		if ($begin > $next)
+			set var $begin = 0
+		end
+
+		# skip over descriptor id
+		set var $begin = $begin + sizeof(long)
+
+		# handle truncated message
+		if ($next - $begin < $info->dict_len)
+			set var $dict_len = $next - $begin
+		else
+			set var $dict_len = $info->dict_len
+		end
+
+		set var $dict = &prb->dict_data_ring.data[$begin]
+	end
+
+	if ($dict_len > 0)
+		set var $idx = 0
+		set var $line = 1
+		while ($idx < $dict_len)
 			if ($line)
 				printf " "
-				set $line = 0
+				set var $line = 0
 			end
-			set $c = $dict[$idx]
+			set var $c = $dict[$idx]
 			if ($c == '\0')
 				printf "\n"
-				set $line = 1
+				set var $line = 1
 			else
 				if ($c < ' ' || $c >= 127 || $c == '\\')
 					printf "\\x%02x", $c
@@ -228,33 +282,40 @@ define dump_log_idx
 					printf "%c", $c
 				end
 			end
-			set $idx = $idx + 1
+			set var $idx = $idx + 1
 		end
 		printf "\n"
 	end
 end
-document dump_log_idx
-	Dump a single log given its index in the log buffer.  The first
-	parameter is the index into log_buf, the second is optional and
-	specified the previous log buffer's flags, used for properly
-	formatting continued lines.
+document dump_record
+	Dump a single record. The first parameter is the descriptor
+	sequence number, the the second is optional and specifies the
+	previous record's flags, used for properly formatting
+	continued lines.
 end
 
 define dmesg
-	set $i = log_first_idx
-	set $end_idx = log_first_idx
-	set $prev_flags = 0
+	set var $desc_committed = 1UL << ((sizeof(long) * 8) - 1)
+	set var $flags_mask = 3UL << ((sizeof(long) * 8) - 2)
+	set var $id_mask = ~$flags_mask
+
+	set var $desc_count = 1U << prb->desc_ring.count_bits
+	set var $prev_flags = 0
+
+	set var $id = prb->desc_ring.tail_id.counter
+	set var $end_id = prb->desc_ring.head_id.counter
 
 	while (1)
-		set $msg = ((struct printk_log *) (log_buf + $i))
-		if ($msg->len == 0)
-			set $i = 0
-		else
-			dump_log_idx $i $prev_flags
-			set $i = $i + $msg->len
-			set $prev_flags = $msg->flags
+		set var $desc = &prb->desc_ring.descs[$id % $desc_count]
+
+		# skip non-committed record
+		if (($desc->state_var.counter & $flags_mask) == $desc_committed)
+			dump_record $desc $prev_flags
+			set var $prev_flags = $desc->info.flags
 		end
-		if ($i == $end_idx)
+
+		set var $id = ($id + 1) & $id_mask
+		if ($id == $end_id)
 			loop_break
 		end
 	end
diff --git a/scripts/gdb/linux/dmesg.py b/scripts/gdb/linux/dmesg.py
index 2fa7bb83885f..6c6022012ea8 100644
--- a/scripts/gdb/linux/dmesg.py
+++ b/scripts/gdb/linux/dmesg.py
@@ -16,8 +16,13 @@ import sys
 
 from linux import utils
 
-printk_log_type = utils.CachedType("struct printk_log")
-
+printk_info_type = utils.CachedType("struct printk_info")
+prb_data_blk_lpos_type = utils.CachedType("struct prb_data_blk_lpos")
+prb_desc_type = utils.CachedType("struct prb_desc")
+prb_desc_ring_type = utils.CachedType("struct prb_desc_ring")
+prb_data_ring_type = utils.CachedType("struct prb_data_ring")
+printk_ringbuffer_type = utils.CachedType("struct printk_ringbuffer")
+atomic_long_type = utils.CachedType("atomic_long_t")
 
 class LxDmesg(gdb.Command):
     """Print Linux kernel log buffer."""
@@ -26,44 +31,102 @@ class LxDmesg(gdb.Command):
         super(LxDmesg, self).__init__("lx-dmesg", gdb.COMMAND_DATA)
 
     def invoke(self, arg, from_tty):
-        log_buf_addr = int(str(gdb.parse_and_eval(
-            "(void *)'printk.c'::log_buf")).split()[0], 16)
-        log_first_idx = int(gdb.parse_and_eval("'printk.c'::log_first_idx"))
-        log_next_idx = int(gdb.parse_and_eval("'printk.c'::log_next_idx"))
-        log_buf_len = int(gdb.parse_and_eval("'printk.c'::log_buf_len"))
-
         inf = gdb.inferiors()[0]
-        start = log_buf_addr + log_first_idx
-        if log_first_idx < log_next_idx:
-            log_buf_2nd_half = -1
-            length = log_next_idx - log_first_idx
-            log_buf = utils.read_memoryview(inf, start, length).tobytes()
-        else:
-            log_buf_2nd_half = log_buf_len - log_first_idx
-            a = utils.read_memoryview(inf, start, log_buf_2nd_half)
-            b = utils.read_memoryview(inf, log_buf_addr, log_next_idx)
-            log_buf = a.tobytes() + b.tobytes()
-
-        length_offset = printk_log_type.get_type()['len'].bitpos // 8
-        text_len_offset = printk_log_type.get_type()['text_len'].bitpos // 8
-        time_stamp_offset = printk_log_type.get_type()['ts_nsec'].bitpos // 8
-        text_offset = printk_log_type.get_type().sizeof
-
-        pos = 0
-        while pos < log_buf.__len__():
-            length = utils.read_u16(log_buf, pos + length_offset)
-            if length == 0:
-                if log_buf_2nd_half == -1:
-                    gdb.write("Corrupted log buffer!\n")
+
+        # read in prb structure
+        prb_addr = int(str(gdb.parse_and_eval("(void *)'printk.c'::prb")).split()[0], 16)
+        sz = printk_ringbuffer_type.get_type().sizeof
+        prb = utils.read_memoryview(inf, prb_addr, sz).tobytes()
+
+        # read in descriptor ring structure
+        off = printk_ringbuffer_type.get_type()['desc_ring'].bitpos // 8
+        addr = prb_addr + off
+        sz = prb_desc_ring_type.get_type().sizeof
+        desc_ring = utils.read_memoryview(inf, addr, sz).tobytes()
+
+        # read in descriptor array
+        off = prb_desc_ring_type.get_type()['count_bits'].bitpos // 8
+        desc_ring_count = 1 << utils.read_u32(desc_ring, off)
+        desc_sz = prb_desc_type.get_type().sizeof
+        off = prb_desc_ring_type.get_type()['descs'].bitpos // 8
+        addr = utils.read_ulong(desc_ring, off)
+        descs = utils.read_memoryview(inf, addr, desc_sz * desc_ring_count).tobytes()
+
+        # read in text data ring structure
+        off = printk_ringbuffer_type.get_type()['text_data_ring'].bitpos // 8
+        addr = prb_addr + off
+        sz = prb_data_ring_type.get_type().sizeof
+        text_data_ring = utils.read_memoryview(inf, addr, sz).tobytes()
+
+        # read in text data
+        off = prb_data_ring_type.get_type()['size_bits'].bitpos // 8
+        text_data_sz = 1 << utils.read_u32(text_data_ring, off)
+        off = prb_data_ring_type.get_type()['data'].bitpos // 8
+        addr = utils.read_ulong(text_data_ring, off)
+        text_data = utils.read_memoryview(inf, addr, text_data_sz).tobytes()
+
+        counter_off = atomic_long_type.get_type()['counter'].bitpos // 8
+
+        sv_off = prb_desc_type.get_type()['state_var'].bitpos // 8
+
+        off = prb_desc_type.get_type()['text_blk_lpos'].bitpos // 8
+        begin_off = off + (prb_data_blk_lpos_type.get_type()['begin'].bitpos // 8)
+        next_off = off + (prb_data_blk_lpos_type.get_type()['next'].bitpos // 8)
+
+        off = prb_desc_type.get_type()['info'].bitpos // 8
+        ts_off = off + printk_info_type.get_type()['ts_nsec'].bitpos // 8
+        len_off = off + printk_info_type.get_type()['text_len'].bitpos // 8
+
+        # definitions from kernel/printk/printk_ringbuffer.h
+        desc_sv_bits = utils.get_long_type().sizeof * 8
+        desc_committed_mask = 1 << (desc_sv_bits - 1)
+        desc_reuse_mask = 1 << (desc_sv_bits - 2)
+        desc_flags_mask = desc_committed_mask | desc_reuse_mask
+        desc_id_mask = ~desc_flags_mask
+
+        # read in tail and head descriptor ids
+        off = prb_desc_ring_type.get_type()['tail_id'].bitpos // 8
+        tail_id = utils.read_u64(desc_ring, off + counter_off)
+        off = prb_desc_ring_type.get_type()['head_id'].bitpos // 8
+        head_id = utils.read_u64(desc_ring, off + counter_off)
+
+        did = tail_id
+        while True:
+            ind = did % desc_ring_count
+            desc_off = desc_sz * ind
+
+            # skip non-committed record
+            state = utils.read_u64(descs, desc_off + sv_off + counter_off) & desc_flags_mask
+            if state != desc_committed_mask:
+                if did == head_id:
                     break
-                pos = log_buf_2nd_half
+                did = (did + 1) & desc_id_mask
                 continue
 
-            text_len = utils.read_u16(log_buf, pos + text_len_offset)
-            text_start = pos + text_offset
-            text = log_buf[text_start:text_start + text_len].decode(
-                encoding='utf8', errors='replace')
-            time_stamp = utils.read_u64(log_buf, pos + time_stamp_offset)
+            begin = utils.read_ulong(descs, desc_off + begin_off) % text_data_sz
+            end = utils.read_ulong(descs, desc_off + next_off) % text_data_sz
+
+            # handle data-less record
+            if begin & 1 == 1:
+                text = ""
+            else:
+                # handle wrapping data block
+                if begin > end:
+                    begin = 0
+
+                # skip over descriptor id
+                text_start = begin + utils.get_long_type().sizeof
+
+                text_len = utils.read_u16(descs, desc_off + len_off)
+
+                # handle truncated message
+                if end - text_start < text_len:
+                    text_len = end - text_start
+
+                text = text_data[text_start:text_start + text_len].decode(
+                    encoding='utf8', errors='replace')
+
+            time_stamp = utils.read_u64(descs, desc_off + ts_off)
 
             for line in text.splitlines():
                 msg = u"[{time:12.6f}] {line}\n".format(
@@ -75,7 +138,9 @@ class LxDmesg(gdb.Command):
                     msg = msg.encode(encoding='utf8', errors='replace')
                 gdb.write(msg)
 
-            pos += length
+            if did == head_id:
+                break
+            did = (did + 1) & desc_id_mask
 
 
 LxDmesg()
-- 
2.20.1

Re: [PATCH 0/2][next] update gdb scripts for lockless printk ringbuffer

[Nick Desaulniers]

On Fri, Aug 14, 2020 at 2:25 PM John Ogness <john.ogness@linutronix.de> wrote:
>
> Hi,
>
> When we brought in the new lockless printk ringbuffer, we overlooked the gdb
> scripts. Here are a set of patches to implement gdb support for the new
> ringbuffer.
>
> John Ogness (2):
>   scripts/gdb: add utils.read_ulong()
>   scripts/gdb: update for lockless printk ringbuffer

Thanks John! For the series:
Tested-by: Nick Desaulniers <ndesaulniers@google.com>

>
>  Documentation/admin-guide/kdump/gdbmacros.txt | 153 ++++++++++++------
>  scripts/gdb/linux/dmesg.py                    | 139 +++++++++++-----
>  scripts/gdb/linux/utils.py                    |   7 +
>  3 files changed, 216 insertions(+), 83 deletions(-)
>
> --
> 2.20.1
>


-- 
Thanks,
~Nick Desaulniers

Re: [PATCH 1/2][next] scripts/gdb: add utils.read_ulong()

[Nick Desaulniers]

On Fri, Aug 14, 2020 at 2:25 PM John Ogness <john.ogness@linutronix.de> wrote:
>
> Add a function for reading unsigned long values, which vary in size
> depending on the architecture.
>
> Signed-off-by: John Ogness <john.ogness@linutronix.de>

Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>

/me wonders if there's any non-ILP32 or LP64 ARCH='s supported by the kernel.

> ---
>
>  based on next-20200814
>
>  scripts/gdb/linux/utils.py | 7 +++++++
>  1 file changed, 7 insertions(+)
>
> diff --git a/scripts/gdb/linux/utils.py b/scripts/gdb/linux/utils.py
> index ea94221dbd39..ff7c1799d588 100644
> --- a/scripts/gdb/linux/utils.py
> +++ b/scripts/gdb/linux/utils.py
> @@ -123,6 +123,13 @@ def read_u64(buffer, offset):
>          return read_u32(buffer, offset + 4) + (read_u32(buffer, offset) << 32)
>
>
> +def read_ulong(buffer, offset):
> +    if get_long_type().sizeof == 8:
> +        return read_u64(buffer, offset)
> +    else:
> +        return read_u32(buffer, offset)
> +
> +
>  target_arch = None
>
>
> --
> 2.20.1
>


-- 
Thanks,
~Nick Desaulniers

Re: [PATCH 0/2][next] update gdb scripts for lockless printk ringbuffer

[Petr Mladek]

On Fri 2020-08-14 23:31:23, John Ogness wrote:
> Hi,
> 
> When we brought in the new lockless printk ringbuffer, we overlooked the gdb
> scripts. Here are a set of patches to implement gdb support for the new
> ringbuffer.
> 
> John Ogness (2):
>   scripts/gdb: add utils.read_ulong()
>   scripts/gdb: update for lockless printk ringbuffer

I am not fluent in the gdb macros and python so I did not try any
deep review. But both patches work for me:

Tested-by: Petr Mladek <pmladek@suse.com>

I am going to give it few more days before pushing just in case there is
another feedback.

Best Regards,
Petr

BTW: Are you aware of https://github.com/crash-python/crash-python project?
     The ambition is to implement "crash" features and even more into
     gdb using python extensions. It similar approach like
     scripts/gdb/

     crash-python is being developed sporadically in waves. It is
     mostly during a week that is dedicated for such projects
     at SUSE. It would be great to get more contributors.

Re: [PATCH 0/2][next] update gdb scripts for lockless printk ringbuffer

[Jan Kiszka]

On 21.08.20 10:08, Petr Mladek wrote:
> On Fri 2020-08-14 23:31:23, John Ogness wrote:
>> Hi,
>>
>> When we brought in the new lockless printk ringbuffer, we overlooked the gdb
>> scripts. Here are a set of patches to implement gdb support for the new
>> ringbuffer.
>>
>> John Ogness (2):
>>   scripts/gdb: add utils.read_ulong()
>>   scripts/gdb: update for lockless printk ringbuffer
> 
> I am not fluent in the gdb macros and python so I did not try any
> deep review. But both patches work for me:
> 
> Tested-by: Petr Mladek <pmladek@suse.com>
> 
> I am going to give it few more days before pushing just in case there is
> another feedback.
> 

Thanks, perfect!

> Best Regards,
> Petr
> 
> BTW: Are you aware of https://github.com/crash-python/crash-python project?
>      The ambition is to implement "crash" features and even more into
>      gdb using python extensions. It similar approach like
>      scripts/gdb/
> 
>      crash-python is being developed sporadically in waves. It is
>      mostly during a week that is dedicated for such projects
>      at SUSE. It would be great to get more contributors.
> 

The problem with all those out-of-tree kernel debugging projects is that
they are even further away from the changes in upstream they need to
adjust to over and over again. It's already hard for scripts/gdb to keep
up as only few people are aware of the dependencies, and it's always
easy to forget. But it's getting better and better here IMHO. And that
was my idea behind pushing things into upstream.

Jan

-- 
Siemens AG, Corporate Technology, CT RDA IOT SES-DE
Corporate Competence Center Embedded Linux

Re: [PATCH 0/2][next] update gdb scripts for lockless printk ringbuffer

[Kieran Bingham]

Hi Petr,

On 21/08/2020 09:55, Jan Kiszka wrote:
> On 21.08.20 10:08, Petr Mladek wrote:
>> On Fri 2020-08-14 23:31:23, John Ogness wrote:
>>> Hi,
>>>
>>> When we brought in the new lockless printk ringbuffer, we overlooked the gdb
>>> scripts. Here are a set of patches to implement gdb support for the new
>>> ringbuffer.
>>>
>>> John Ogness (2):
>>>   scripts/gdb: add utils.read_ulong()
>>>   scripts/gdb: update for lockless printk ringbuffer
>>
>> I am not fluent in the gdb macros and python so I did not try any
>> deep review. But both patches work for me:
>>
>> Tested-by: Petr Mladek <pmladek@suse.com>
>>
>> I am going to give it few more days before pushing just in case there is
>> another feedback.

Before 'pushing' ?

What context do you mean here? These patches go through AKPM don't they?
Did I miss some update to procedures?

>>
> 
> Thanks, perfect!
> 
>> Best Regards,
>> Petr
>>
>> BTW: Are you aware of https://github.com/crash-python/crash-python project?
>>      The ambition is to implement "crash" features and even more into
>>      gdb using python extensions. It similar approach like
>>      scripts/gdb/
>>
>>      crash-python is being developed sporadically in waves. It is
>>      mostly during a week that is dedicated for such projects
>>      at SUSE. It would be great to get more contributors.
>>
> 
> The problem with all those out-of-tree kernel debugging projects is that
> they are even further away from the changes in upstream they need to
> adjust to over and over again. It's already hard for scripts/gdb to keep
> up as only few people are aware of the dependencies, and it's always
> easy to forget. But it's getting better and better here IMHO. And that
> was my idea behind pushing things into upstream.

Seconding that, and having also investigated the crash projects in
previous work. I really wish there was more alignment to the kernel ;-)

/me ponders what happened to the kernel awareness integrations on GDB...
I know others have been investigating too, If only I had time ...

> Jan
> 


-- 
--
Kieran

Re: [PATCH 0/2][next] update gdb scripts for lockless printk ringbuffer

[Petr Mladek]

On Mon 2020-08-24 10:20:53, Kieran Bingham wrote:
> Hi Petr,
> 
> On 21/08/2020 09:55, Jan Kiszka wrote:
> > On 21.08.20 10:08, Petr Mladek wrote:
> >> On Fri 2020-08-14 23:31:23, John Ogness wrote:
> >>> Hi,
> >>>
> >>> When we brought in the new lockless printk ringbuffer, we overlooked the gdb
> >>> scripts. Here are a set of patches to implement gdb support for the new
> >>> ringbuffer.
> >>>
> >>> John Ogness (2):
> >>>   scripts/gdb: add utils.read_ulong()
> >>>   scripts/gdb: update for lockless printk ringbuffer
> >>
> >> I am not fluent in the gdb macros and python so I did not try any
> >> deep review. But both patches work for me:
> >>
> >> Tested-by: Petr Mladek <pmladek@suse.com>
> >>
> >> I am going to give it few more days before pushing just in case there is
> >> another feedback.
> 
> Before 'pushing' ?
> 
> What context do you mean here? These patches go through AKPM don't they?
> Did I miss some update to procedures?

Both patches should go into mainline together with the lockless printk
ring buffer. It is already in linux-next via printk/linux.git,
branch printk-rework.

The plan is to get it into mainline when pr_cont() handling is solved.
It is more complicated than we hoped for, see
https://lore.kernel.org/r/20200824103538.31446-1-john.ogness@linutronix.de
It is still not clear whether it will be ready for 5.10.

Andrew, would you mind when I take the three gdb/lockless-printk
related changes via printk tree to avoid synchronization problems?

Best Regards,
Petr

Re: [PATCH 0/2][next] update gdb scripts for lockless printk ringbuffer

[Jan Kiszka]

On 25.08.20 14:35, Petr Mladek wrote:
> On Mon 2020-08-24 10:20:53, Kieran Bingham wrote:
>> Hi Petr,
>>
>> On 21/08/2020 09:55, Jan Kiszka wrote:
>>> On 21.08.20 10:08, Petr Mladek wrote:
>>>> On Fri 2020-08-14 23:31:23, John Ogness wrote:
>>>>> Hi,
>>>>>
>>>>> When we brought in the new lockless printk ringbuffer, we overlooked the gdb
>>>>> scripts. Here are a set of patches to implement gdb support for the new
>>>>> ringbuffer.
>>>>>
>>>>> John Ogness (2):
>>>>>   scripts/gdb: add utils.read_ulong()
>>>>>   scripts/gdb: update for lockless printk ringbuffer
>>>>
>>>> I am not fluent in the gdb macros and python so I did not try any
>>>> deep review. But both patches work for me:
>>>>
>>>> Tested-by: Petr Mladek <pmladek@suse.com>
>>>>
>>>> I am going to give it few more days before pushing just in case there is
>>>> another feedback.
>>
>> Before 'pushing' ?
>>
>> What context do you mean here? These patches go through AKPM don't they?
>> Did I miss some update to procedures?
> 
> Both patches should go into mainline together with the lockless printk
> ring buffer. It is already in linux-next via printk/linux.git,
> branch printk-rework.
> 
> The plan is to get it into mainline when pr_cont() handling is solved.
> It is more complicated than we hoped for, see
> https://lore.kernel.org/r/20200824103538.31446-1-john.ogness@linutronix.de
> It is still not clear whether it will be ready for 5.10.
> 
> Andrew, would you mind when I take the three gdb/lockless-printk
> related changes via printk tree to avoid synchronization problems?

From my POV, that would be best in this case - but actually also in
other cases where developers happen to notice the dependency between
their refactorings and gdb scripts.

Jan

-- 
Siemens AG, Corporate Technology, CT RDA IOT SES-DE
Corporate Competence Center Embedded Linux

Re: [PATCH 0/2][next] update gdb scripts for lockless printk ringbuffer

[Andrew Morton]

On Tue, 25 Aug 2020 14:35:42 +0200 Petr Mladek <pmladek@suse.com> wrote:

> Andrew, would you mind when I take the three gdb/lockless-printk
> related changes via printk tree to avoid synchronization problems?

No probs.  If such patches turn up in linux-next I just drop my copy.
After checking that the patches fully match...

Re: [PATCH 0/2][next] update gdb scripts for lockless printk ringbuffer

[Petr Mladek]

On Tue 2020-08-25 17:17:56, Andrew Morton wrote:
> On Tue, 25 Aug 2020 14:35:42 +0200 Petr Mladek <pmladek@suse.com> wrote:
> 
> > Andrew, would you mind when I take the three gdb/lockless-printk
> > related changes via printk tree to avoid synchronization problems?
> 
> No probs.  If such patches turn up in linux-next I just drop my copy.
> After checking that the patches fully match...

I have just pushed the two patches into printk/linux.git, branch
printk-rework.

Andrew's typo fix has been squashed into the 2nd patch.

Best Regards,
Petr