From: "Jérôme Pouiller" <jerome.pouiller@silabs.com>
To: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: driverdevel <devel@driverdev.osuosl.org>,
linux-wireless <linux-wireless@vger.kernel.org>,
netdev <netdev@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Kalle Valo <kvalo@codeaurora.org>,
"David S . Miller" <davem@davemloft.net>
Subject: Re: [PATCH 13/17] staging: wfx: fix endianness of the field 'len'
Date: Tue, 12 May 2020 11:25:47 +0200 [thread overview]
Message-ID: <1922297.S9MP3OIeVN@pc-42> (raw)
In-Reply-To: <CAMuHMdVZxy+FZGPhDxotCBeEX3O4ZMkmGAwmVFXQE9ZoijDN5g@mail.gmail.com>
On Tuesday 12 May 2020 09:43:34 CEST Geert Uytterhoeven wrote:
> Hi Jerome,
>
> On Mon, May 11, 2020 at 5:53 PM Jerome Pouiller
> <Jerome.Pouiller@silabs.com> wrote:
> > From: Jérôme Pouiller <jerome.pouiller@silabs.com>
> >
> > The struct hif_msg is received from the hardware. So, it declared as
> > little endian. However, it is also accessed from many places in the
> > driver. Sparse complains about that:
> >
> > drivers/staging/wfx/bh.c:88:32: warning: restricted __le16 degrades to integer
> > drivers/staging/wfx/bh.c:88:32: warning: restricted __le16 degrades to integer
> > drivers/staging/wfx/bh.c:93:32: warning: restricted __le16 degrades to integer
> > drivers/staging/wfx/bh.c:93:32: warning: cast to restricted __le16
> > drivers/staging/wfx/bh.c:93:32: warning: restricted __le16 degrades to integer
> > drivers/staging/wfx/bh.c:121:25: warning: incorrect type in argument 2 (different base types)
> > drivers/staging/wfx/bh.c:121:25: expected unsigned int len
> > drivers/staging/wfx/bh.c:121:25: got restricted __le16 [usertype] len
> > drivers/staging/wfx/hif_rx.c:27:22: warning: restricted __le16 degrades to integer
> > drivers/staging/wfx/hif_rx.c:347:39: warning: incorrect type in argument 7 (different base types)
> > drivers/staging/wfx/hif_rx.c:347:39: expected unsigned int [usertype] len
> > drivers/staging/wfx/hif_rx.c:347:39: got restricted __le16 const [usertype] len
> > drivers/staging/wfx/hif_rx.c:365:39: warning: incorrect type in argument 7 (different base types)
> > drivers/staging/wfx/hif_rx.c:365:39: expected unsigned int [usertype] len
> > drivers/staging/wfx/hif_rx.c:365:39: got restricted __le16 const [usertype] len
> > drivers/staging/wfx/./traces.h:195:1: warning: incorrect type in assignment (different base types)
> > drivers/staging/wfx/./traces.h:195:1: expected int msg_len
> > drivers/staging/wfx/./traces.h:195:1: got restricted __le16 const [usertype] len
> > drivers/staging/wfx/./traces.h:195:1: warning: incorrect type in assignment (different base types)
> > drivers/staging/wfx/./traces.h:195:1: expected int msg_len
> > drivers/staging/wfx/./traces.h:195:1: got restricted __le16 const [usertype] len
> > drivers/staging/wfx/debug.c:319:20: warning: restricted __le16 degrades to integer
> > drivers/staging/wfx/secure_link.c:85:27: warning: restricted __le16 degrades to integer
> > drivers/staging/wfx/secure_link.c:85:27: warning: restricted __le16 degrades to integer
>
> Thanks for your patch!
>
> > In order to make Sparse happy and to keep access from the driver easy,
> > this patch declare 'len' with native endianness.
> >
> > On reception of hardware data, this patch takes care to do byte-swap and
> > keep Sparse happy.
>
> Which means sparse can no longer do any checking on the field,
> and new bugs may/will creep in in the future, unnoticed.
>
> > --- a/drivers/staging/wfx/hif_api_general.h
> > +++ b/drivers/staging/wfx/hif_api_general.h
> > @@ -23,7 +23,10 @@
> > #define HIF_COUNTER_MAX 7
> >
> > struct hif_msg {
> > - __le16 len;
> > + // len is in fact little endian. However, it is widely used in the
> > + // driver, so we declare it in native byte order and we reorder just
> > + // before/after send/receive it (see bh.c).
> > + u16 len;
>
> While there's a small penalty associated with always doing the conversion
> on big-endian platforms, it will probably be lost in the noise anyway.
I have made the changes to show you that the code is far more complicated
with a le16... and the result was not as complicated as I expected...
I am going to post a v2.
--
Jérôme Pouiller
next prev parent reply other threads:[~2020-05-12 9:25 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-11 15:49 [PATCH 00/17] staging: wfx: fix support for big-endian hosts Jerome Pouiller
2020-05-11 15:49 ` [PATCH 01/17] staging: wfx: fix use of cpu_to_le32 instead of le32_to_cpu Jerome Pouiller
2020-05-11 15:49 ` [PATCH 02/17] staging: wfx: take advantage of le32_to_cpup() Jerome Pouiller
2020-05-11 15:49 ` [PATCH 03/17] staging: wfx: fix cast operator Jerome Pouiller
2020-05-11 15:49 ` [PATCH 04/17] staging: wfx: fix wrong bytes order Jerome Pouiller
2020-05-11 15:49 ` [PATCH 05/17] staging: wfx: fix output of rx_stats on big endian hosts Jerome Pouiller
2020-05-11 15:49 ` [PATCH 06/17] staging: wfx: fix endianness of fields media_delay and tx_queue_delay Jerome Pouiller
2020-05-11 15:49 ` [PATCH 07/17] staging: wfx: fix endianness of hif_req_read_mib fields Jerome Pouiller
2020-05-11 15:49 ` [PATCH 08/17] staging: wfx: fix access to le32 attribute 'ps_mode_error' Jerome Pouiller
2020-05-11 15:49 ` [PATCH 09/17] staging: wfx: fix access to le32 attribute 'event_id' Jerome Pouiller
2020-05-11 15:49 ` [PATCH 10/17] staging: wfx: fix access to le32 attribute 'indication_type' Jerome Pouiller
2020-05-11 15:49 ` [PATCH 11/17] staging: wfx: declare the field 'packet_id' with native byte order Jerome Pouiller
2020-05-11 15:49 ` [PATCH 12/17] staging: wfx: fix endianness of the struct hif_ind_startup Jerome Pouiller
2020-05-11 15:49 ` [PATCH 13/17] staging: wfx: fix endianness of the field 'len' Jerome Pouiller
2020-05-11 21:59 ` kbuild test robot
2020-05-12 7:43 ` Geert Uytterhoeven
2020-05-12 9:25 ` Jérôme Pouiller [this message]
2020-05-11 15:49 ` [PATCH 14/17] staging: wfx: fix endianness of the field 'status' Jerome Pouiller
2020-05-11 15:49 ` [PATCH 15/17] staging: wfx: fix endianness of the field 'num_tx_confs' Jerome Pouiller
2020-05-11 15:49 ` [PATCH 16/17] staging: wfx: fix endianness of the field 'channel_number' Jerome Pouiller
2020-05-11 15:49 ` [PATCH 17/17] staging: wfx: update TODO Jerome Pouiller
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