9ad06ebb9a
The current codebase makes use of the zero-length array language
extension to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1][2],
introduced in C99:
struct foo {
int stuff;
struct boo array[];
};
By making use of the mechanism above, we will get a compiler warning
in case the flexible array does not occur last in the structure, which
will help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.
Also, notice that, dynamic memory allocations won't be affected by
this change:
"Flexible array members have incomplete type, and so the sizeof operator
may not be applied. As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]
sizeof(flexible-array-member) triggers a warning because flexible array
members have incomplete type[1]. There are some instances of code in
which the sizeof operator is being incorrectly/erroneously applied to
zero-length arrays and the result is zero. Such instances may be hiding
some bugs. So, this work (flexible-array member conversions) will also
help to get completely rid of those sorts of issues.
This issue was found with the help of Coccinelle.
[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 7649773293 ("cxgb3/l2t: Fix undefined behaviour")
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Link: https://lore.kernel.org/r/20200507192223.GA16335@embeddedor
Signed-off-by: Takashi Iwai <tiwai@suse.de>
90 lines
2.1 KiB
C
90 lines
2.1 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef USBUSX2Y_H
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#define USBUSX2Y_H
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#include "../usbaudio.h"
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#include "../midi.h"
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#include "usbus428ctldefs.h"
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#define NRURBS 2
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#define URBS_AsyncSeq 10
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#define URB_DataLen_AsyncSeq 32
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struct snd_usX2Y_AsyncSeq {
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struct urb *urb[URBS_AsyncSeq];
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char *buffer;
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};
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struct snd_usX2Y_urbSeq {
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int submitted;
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int len;
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struct urb *urb[];
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};
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#include "usx2yhwdeppcm.h"
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struct usX2Ydev {
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struct usb_device *dev;
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int card_index;
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int stride;
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struct urb *In04urb;
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void *In04Buf;
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char In04Last[24];
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unsigned In04IntCalls;
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struct snd_usX2Y_urbSeq *US04;
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wait_queue_head_t In04WaitQueue;
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struct snd_usX2Y_AsyncSeq AS04;
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unsigned int rate,
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format;
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int chip_status;
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struct mutex pcm_mutex;
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struct us428ctls_sharedmem *us428ctls_sharedmem;
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int wait_iso_frame;
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wait_queue_head_t us428ctls_wait_queue_head;
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struct snd_usX2Y_hwdep_pcm_shm *hwdep_pcm_shm;
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struct snd_usX2Y_substream *subs[4];
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struct snd_usX2Y_substream * volatile prepare_subs;
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wait_queue_head_t prepare_wait_queue;
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struct list_head midi_list;
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struct list_head pcm_list;
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int pcm_devs;
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};
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struct snd_usX2Y_substream {
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struct usX2Ydev *usX2Y;
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struct snd_pcm_substream *pcm_substream;
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int endpoint;
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unsigned int maxpacksize; /* max packet size in bytes */
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atomic_t state;
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#define state_STOPPED 0
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#define state_STARTING1 1
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#define state_STARTING2 2
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#define state_STARTING3 3
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#define state_PREPARED 4
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#define state_PRERUNNING 6
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#define state_RUNNING 8
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int hwptr; /* free frame position in the buffer (only for playback) */
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int hwptr_done; /* processed frame position in the buffer */
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int transfer_done; /* processed frames since last period update */
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struct urb *urb[NRURBS]; /* data urb table */
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struct urb *completed_urb;
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char *tmpbuf; /* temporary buffer for playback */
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};
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#define usX2Y(c) ((struct usX2Ydev *)(c)->private_data)
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int usX2Y_audio_create(struct snd_card *card);
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int usX2Y_AsyncSeq04_init(struct usX2Ydev *usX2Y);
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int usX2Y_In04_init(struct usX2Ydev *usX2Y);
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#define NAME_ALLCAPS "US-X2Y"
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#endif
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