From: Wolfram Sang <wsa@the-dreams.de>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: John Sperbeck <jsperbeck@google.com>,
Ingo Molnar <mingo@redhat.com>,
linux-i2c@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] i2c: core-smbus: don't trace smbus_reply data on errors
Date: Tue, 5 Feb 2019 13:13:57 +0100 [thread overview]
Message-ID: <20190205121353.GC1045@kunai> (raw)
In-Reply-To: <20190103214927.2bf947ca@vmware.local.home>
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On Thu, Jan 03, 2019 at 09:49:27PM -0500, Steven Rostedt wrote:
> On Thu, 3 Jan 2019 16:42:03 -0800
> John Sperbeck <jsperbeck@google.com> wrote:
>
> > If an smbus transfer fails, there's no guarantee that the output
> > buffer was written. So, avoid copying from the output buffer when
> > tracing after an error. This was 'mostly harmless', but would trip
> > up kasan checking if left-over cruft in byte 0 is a large length,
> > causing us to read from unwritten memory.
> >
> > Signed-off-by: John Sperbeck <jsperbeck@google.com>
> > ---
> > drivers/i2c/i2c-core-smbus.c | 2 +-
> > include/trace/events/smbus.h | 10 +++++-----
> > 2 files changed, 6 insertions(+), 6 deletions(-)
> >
> > diff --git a/drivers/i2c/i2c-core-smbus.c b/drivers/i2c/i2c-core-smbus.c
> > index 9cd66cabb84f..132119112596 100644
> > --- a/drivers/i2c/i2c-core-smbus.c
> > +++ b/drivers/i2c/i2c-core-smbus.c
> > @@ -585,7 +585,7 @@ s32 __i2c_smbus_xfer(struct i2c_adapter *adapter, u16 addr,
> > trace:
> > /* If enabled, the reply tracepoint is conditional on read_write. */
> > trace_smbus_reply(adapter, addr, flags, read_write,
> > - command, protocol, data);
> > + command, protocol, data, res);
> > trace_smbus_result(adapter, addr, flags, read_write,
> > command, protocol, res);
> >
> > diff --git a/include/trace/events/smbus.h b/include/trace/events/smbus.h
> > index d2fb6e1d3e10..b6376a7c7e74 100644
> > --- a/include/trace/events/smbus.h
> > +++ b/include/trace/events/smbus.h
> > @@ -138,8 +138,8 @@ TRACE_EVENT_CONDITION(smbus_reply,
> > TP_PROTO(const struct i2c_adapter *adap,
> > u16 addr, unsigned short flags,
> > char read_write, u8 command, int protocol,
> > - const union i2c_smbus_data *data),
> > - TP_ARGS(adap, addr, flags, read_write, command, protocol, data),
> > + const union i2c_smbus_data *data, int res),
> > + TP_ARGS(adap, addr, flags, read_write, command, protocol, data, res),
> > TP_CONDITION(read_write == I2C_SMBUS_READ),
>
> Hmm, instead of tracing nothing, as this is already a "conditional
> trace event", why not add to that condition:
>
> TP_CONDITION(res >= 0 && read_write == I2C_SMBUS_READ),
>
> Unless you want to still trace some data on failure.
John, any comment to this?
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next prev parent reply other threads:[~2019-02-05 12:14 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-04 0:42 [PATCH] i2c: core-smbus: don't trace smbus_reply data on errors John Sperbeck
2019-01-04 2:49 ` Steven Rostedt
2019-02-05 12:13 ` Wolfram Sang [this message]
2019-02-05 17:19 ` John Sperbeck
2019-02-05 19:08 ` Wolfram Sang
2019-02-11 3:40 ` [PATCH v2] " John Sperbeck
2019-02-11 14:24 ` Steven Rostedt
2019-02-11 21:43 ` John Sperbeck
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