From: Chuck Lever III <chuck.lever@oracle.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Linux NFS Mailing List <linux-nfs@vger.kernel.org>,
David Wysochanski <dwysocha@redhat.com>,
Bruce Fields <bfields@fieldses.org>
Subject: Re: [PATCH v2 01/25] NFSD: Fix TP_printk() format specifier in trace_nfsd_dirent()
Date: Mon, 12 Jul 2021 15:18:05 +0000 [thread overview]
Message-ID: <BC78B174-91E3-44C5-8B49-2C5F34BA8823@oracle.com> (raw)
In-Reply-To: <20210513105018.7539996a@gandalf.local.home>
Hello Steven-
> On May 13, 2021, at 10:50 AM, Steven Rostedt <rostedt@goodmis.org> wrote:
>
> On Wed, 12 May 2021 16:52:05 +0000
> Chuck Lever III <chuck.lever@oracle.com> wrote:
>
>> The underlying need is to support non-NUL-terminated C strings.
>>
>> I assumed that since the commentary around 9a6944fee68e claims
>> the proper way to trace C strings is to use __string and friends,
>> and those do not support non-NUL-terminated strings, that such
>> strings are really not first-class citizens. Thus I concluded
>> that my use of '%.*s' was incorrect.
>>
>> Having some __string-style helpers that can deal with such
>> strings would be valuable.
>
> I guess the best I can do is a strncpy version, that will add the '\0' in
> the ring buffer. That way we don't need to save the length as well (length
> would need to be at least 4 bytes, where as '\0' is one).
>
> Something like this?
I don't see this change in v5.14-rc1.
> I added "__string_len()" and "__assign_str_len()". You use them just like
> __string() and __assign_str() but add a max length that you want to use
> (although, it will always allocate "len" regardless if the string is
> smaller). Then use __get_str() just like you use __string().
>
> Would something like that work?
>
> -- Steve
>
> diff --git a/include/trace/trace_events.h b/include/trace/trace_events.h
> index 8268bf747d6f..7ab23535a0c8 100644
> --- a/include/trace/trace_events.h
> +++ b/include/trace/trace_events.h
> @@ -102,6 +102,9 @@ TRACE_MAKE_SYSTEM_STR();
> #undef __string
> #define __string(item, src) __dynamic_array(char, item, -1)
>
> +#undef __string_len
> +#define __string_len(item, src, len) __dynamic_array(char, item, -1)
> +
> #undef __bitmask
> #define __bitmask(item, nr_bits) __dynamic_array(char, item, -1)
>
> @@ -197,6 +200,9 @@ TRACE_MAKE_SYSTEM_STR();
> #undef __string
> #define __string(item, src) __dynamic_array(char, item, -1)
>
> +#undef __string_len
> +#define __string_len(item, src, len) __dynamic_array(char, item, -1)
> +
> #undef __bitmask
> #define __bitmask(item, nr_bits) __dynamic_array(unsigned long, item, -1)
>
> @@ -444,6 +450,9 @@ static struct trace_event_functions trace_event_type_funcs_##call = { \
> #undef __string
> #define __string(item, src) __dynamic_array(char, item, -1)
>
> +#undef __string_len
> +#define __string_len(item, src, len) __dynamic_array(char, item, -1)
> +
> #undef __bitmask
> #define __bitmask(item, nr_bits) __dynamic_array(unsigned long, item, -1)
>
> @@ -492,6 +501,9 @@ static struct trace_event_fields trace_event_fields_##call[] = { \
> #define __string(item, src) __dynamic_array(char, item, \
> strlen((src) ? (const char *)(src) : "(null)") + 1)
>
> +#undef __string_len
> +#define __string_len(item, src, len) __dynamic_array(char, item, (len) + 1)
> +
> /*
> * __bitmask_size_in_bytes_raw is the number of bytes needed to hold
> * num_possible_cpus().
> @@ -655,10 +667,18 @@ static inline notrace int trace_event_get_offsets_##call( \
> #undef __string
> #define __string(item, src) __dynamic_array(char, item, -1)
>
> +#undef __string_len
> +#define __string_len(item, src, len) __dynamic_array(char, item, -1)
> +
> #undef __assign_str
> #define __assign_str(dst, src) \
> strcpy(__get_str(dst), (src) ? (const char *)(src) : "(null)");
>
> +#undef __assign_str_len
> +#define __assign_str_len(dst, src, len) \
> + strncpy(__get_str(dst), (src) ? (const char *)(src) : "(null)", len); \
> + __get_str(dst)[len] = '\0';
> +
> #undef __bitmask
> #define __bitmask(item, nr_bits) __dynamic_array(unsigned long, item, -1)
>
>
>
--
Chuck Lever
next prev parent reply other threads:[~2021-07-12 15:18 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-12 15:34 [PATCH v2 00/25] NFSD callback and lease management observability Chuck Lever
2021-05-12 15:35 ` [PATCH v2 01/25] NFSD: Fix TP_printk() format specifier in trace_nfsd_dirent() Chuck Lever
2021-05-12 16:26 ` Steven Rostedt
2021-05-12 16:52 ` Chuck Lever III
2021-05-13 14:50 ` Steven Rostedt
2021-05-13 14:53 ` Chuck Lever III
2021-05-13 15:02 ` Steven Rostedt
2021-05-13 15:10 ` Chuck Lever III
2021-05-13 18:43 ` Chuck Lever III
2021-05-13 19:00 ` Steven Rostedt
2021-05-13 19:08 ` Chuck Lever III
2021-05-13 19:17 ` Steven Rostedt
2021-05-13 20:01 ` Chuck Lever III
2021-07-12 15:18 ` Chuck Lever III [this message]
2021-07-12 17:09 ` Steven Rostedt
2021-05-12 16:53 ` Steven Rostedt
2021-05-12 15:35 ` [PATCH v2 02/25] NFSD: Fix TP_printk() format specifier in nfsd_clid_class Chuck Lever
2021-05-12 15:35 ` [PATCH v2 03/25] NFSD: Add nfsd_clid_cred_mismatch tracepoint Chuck Lever
2021-05-12 15:35 ` [PATCH v2 04/25] NFSD: Add nfsd_clid_verf_mismatch tracepoint Chuck Lever
2021-05-12 15:35 ` [PATCH v2 05/25] NFSD: Remove trace_nfsd_clid_inuse_err Chuck Lever
2021-05-12 15:35 ` [PATCH v2 06/25] NFSD: Add nfsd_clid_confirmed tracepoint Chuck Lever
2021-05-12 15:35 ` [PATCH v2 07/25] NFSD: Add nfsd_clid_reclaim_complete tracepoint Chuck Lever
2021-05-12 15:35 ` [PATCH v2 08/25] NFSD: Add nfsd_clid_destroyed tracepoint Chuck Lever
2021-05-12 15:35 ` [PATCH v2 09/25] NFSD: Add a couple more nfsd_clid_expired call sites Chuck Lever
2021-05-13 16:42 ` David Wysochanski
2021-05-13 17:05 ` Chuck Lever III
2021-05-12 15:36 ` [PATCH v2 10/25] NFSD: Add an RPC authflavor tracepoint display helper Chuck Lever
2021-05-12 15:36 ` [PATCH v2 11/25] NFSD: Add tracepoints for SETCLIENTID edge cases Chuck Lever
2021-05-12 15:36 ` [PATCH v2 12/25] NFSD: Add tracepoints for EXCHANGEID " Chuck Lever
2021-05-12 15:36 ` [PATCH v2 13/25] NFSD: Constify @fh argument of knfsd_fh_hash() Chuck Lever
2021-05-12 15:36 ` [PATCH v2 14/25] NFSD: Capture every CB state transition Chuck Lever
2021-05-12 15:36 ` [PATCH v2 15/25] NFSD: Drop TRACE_DEFINE_ENUM for NFSD4_CB_<state> macros Chuck Lever
2021-05-12 15:36 ` [PATCH v2 16/25] NFSD: Add cb_lost tracepoint Chuck Lever
2021-05-12 15:36 ` [PATCH v2 17/25] NFSD: Adjust cb_shutdown tracepoint Chuck Lever
2021-05-12 15:36 ` [PATCH v2 18/25] NFSD: Remove spurious cb_setup_err tracepoint Chuck Lever
2021-05-12 15:37 ` [PATCH v2 19/25] NFSD: Enhance the nfsd_cb_setup tracepoint Chuck Lever
2021-05-12 15:37 ` [PATCH v2 20/25] NFSD: Add an nfsd_cb_lm_notify tracepoint Chuck Lever
2021-05-12 15:37 ` [PATCH v2 21/25] NFSD: Add an nfsd_cb_offload tracepoint Chuck Lever
2021-05-12 15:37 ` [PATCH v2 22/25] NFSD: Replace the nfsd_deleg_break tracepoint Chuck Lever
2021-05-12 15:37 ` [PATCH v2 23/25] NFSD: Add an nfsd_cb_probe tracepoint Chuck Lever
2021-05-12 15:37 ` [PATCH v2 24/25] NFSD: Remove the nfsd_cb_work and nfsd_cb_done tracepoints Chuck Lever
2021-05-12 15:37 ` [PATCH v2 25/25] NFSD: Update nfsd_cb_args tracepoint Chuck Lever
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