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Date: Thu, 18 Aug 2011 14:28:47 +0200
From: "Michal Nazarewicz" <mina86@...a86.com>
To: "Felipe Balbi" <balbi@...com>,
"Greg Kroah-Hartman" <gregkh@...e.de>,
"Per Forlin" <per.forlin@...ricsson.com>
Cc: linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
linaro-dev@...ts.linaro.org, "Per Forlin" <per.forlin@...aro.org>
Subject: Re: [PATCH v4] usb: gadget: storage_common: make FSG_NUM_BUFFERS
variable size
On Thu, 18 Aug 2011 11:28:46 +0200, Per Forlin wrote:
> diff --git a/drivers/usb/gadget/f_mass_storage.c
> b/drivers/usb/gadget/f_mass_storage.c
> index 5b93395..3e546d9 100644
> --- a/drivers/usb/gadget/f_mass_storage.c
> +++ b/drivers/usb/gadget/f_mass_storage.c
> @@ -363,7 +363,6 @@ struct fsg_common {
> struct fsg_buffhd *next_buffhd_to_fill;
> struct fsg_buffhd *next_buffhd_to_drain;
> - struct fsg_buffhd buffhds[FSG_NUM_BUFFERS];
> int cmnd_size;
> u8 cmnd[MAX_COMMAND_SIZE];
> @@ -407,6 +406,8 @@ struct fsg_common {
> char inquiry_string[8 + 16 + 4 + 1];
> struct kref ref;
> + /* Must be the last entry */
> + struct fsg_buffhd buffhds[0];
I would rather see it as “struct fsg_buffhd *buffhds;” since this change
requires both mass_storage.c and multi.c to be changed.
Alternatively, revert the possibility for fsg_common_init() to take struct
fsg_common as an argument, but that would be more intrusive I think and
I would prefer the former.
> };
> struct fsg_config {
> @@ -2728,12 +2729,15 @@ static struct fsg_common *fsg_common_init(struct
> fsg_common *common,
> /* Allocate? */
> if (!common) {
> - common = kzalloc(sizeof *common, GFP_KERNEL);
> + common = kzalloc(sizeof(struct fsg_common) +
> + sizeof(struct fsg_buffhd) * FSG_NUM_BUFFERS,
> + GFP_KERNEL);
Better yet:
kzalloc(sizeof *common + FSG_NUM_BUFFERS * sizeof *(common->buffhds),
GFP_KERNEL);
but like I've said, I would prefer that buffhds is a separate array.
> diff --git a/drivers/usb/gadget/file_storage.c
> b/drivers/usb/gadget/file_storage.c
> index 639e14a..21d366d 100644
> --- a/drivers/usb/gadget/file_storage.c
> +++ b/drivers/usb/gadget/file_storage.c
> @@ -461,7 +461,6 @@ struct fsg_dev {
> struct fsg_buffhd *next_buffhd_to_fill;
> struct fsg_buffhd *next_buffhd_to_drain;
> - struct fsg_buffhd buffhds[FSG_NUM_BUFFERS];
> int thread_wakeup_needed;
> struct completion thread_notifier;
> @@ -488,6 +487,8 @@ struct fsg_dev {
> unsigned int nluns;
> struct fsg_lun *luns;
> struct fsg_lun *curlun;
> + /* Must be the last entry */
> + struct fsg_buffhd buffhds[0];
IIRC, C99's way of doing it is: “struct fsg_buffhd buffhds[];”.
> };
> typedef void (*fsg_routine_t)(struct fsg_dev *);
> @@ -3587,7 +3588,9 @@ static int __init fsg_alloc(void)
> {
> struct fsg_dev *fsg;
> - fsg = kzalloc(sizeof *fsg, GFP_KERNEL);
> + fsg = kzalloc(sizeof(struct fsg_dev) +
> + sizeof(struct fsg_buffhd) * FSG_NUM_BUFFERS, GFP_KERNEL);
> +
Better yet:
kzalloc(sizeof *fsg + FSG_NUM_BUFFERS * sizeof *(fsg->buffhds),
GFP_KERNEL);
> if (!fsg)
> return -ENOMEM;
> spin_lock_init(&fsg->lock);
> diff --git a/drivers/usb/gadget/mass_storage.c
> b/drivers/usb/gadget/mass_storage.c
> index d3eb274..67c58d0 100644
> --- a/drivers/usb/gadget/mass_storage.c
> +++ b/drivers/usb/gadget/mass_storage.c
> @@ -116,9 +116,8 @@ static int __init msg_do_config(struct
> usb_configuration *c)
> static const struct fsg_operations ops = {
> .thread_exits = msg_thread_exits,
> };
> - static struct fsg_common common;
> + struct fsg_common *common = NULL;
> - struct fsg_common *retp;
> struct fsg_config config;
> int ret;
> @@ -130,12 +129,12 @@ static int __init msg_do_config(struct
> usb_configuration *c)
> fsg_config_from_params(&config, &mod_data);
> config.ops = &ops;
> - retp = fsg_common_init(&common, c->cdev, &config);
> - if (IS_ERR(retp))
> - return PTR_ERR(retp);
> + common = fsg_common_init(common, c->cdev, &config);
The first argument should be NULL.
> + if (IS_ERR(common))
> + return PTR_ERR(common);
> - ret = fsg_bind_config(c->cdev, c, &common);
> - fsg_common_put(&common);
> + ret = fsg_bind_config(c->cdev, c, common);
> + fsg_common_put(common);
> return ret;
> }
> diff --git a/drivers/usb/gadget/storage_common.c
> b/drivers/usb/gadget/storage_common.c
> index d3dd227..197eace 100644
> --- a/drivers/usb/gadget/storage_common.c
> +++ b/drivers/usb/gadget/storage_common.c
> @@ -262,8 +262,24 @@ static struct fsg_lun *fsg_lun_from_dev(struct
> device *dev)
> #define EP0_BUFSIZE 256
> #define DELAYED_STATUS (EP0_BUFSIZE + 999) /* An impossibly large value
> */
> -/* Number of buffers we will use. 2 is enough for double-buffering */
> -#define FSG_NUM_BUFFERS 2
> +#ifdef CONFIG_USB_DEBUG
> +
> +static unsigned int fsg_num_buffers =
> CONFIG_USB_GADGET_STORAGE_NUM_BUFFERS;
> +module_param(fsg_num_buffers, uint, S_IRUGO);
> +MODULE_PARM_DESC(fsg_num_buffers, "Number of pipeline buffers");
> +#define FSG_NUM_BUFFERS fsg_num_buffers
Could we get rid of the macro all together, and just stick to
“fsg_num_buffers” variable? Upper case name suggest that it's
a compile time constant which is not true.
> +#else
> +
> +/*
> + * Number of buffers we will use.
> + * 2 is usually enough for good buffering pipeline
> + */
> +#define FSG_NUM_BUFFERS CONFIG_USB_GADGET_STORAGE_NUM_BUFFERS
Similarly, I'd change the name to lowercase as to reflect that sometimes
it may be not a compile-time constant.
> +#endif /* CONFIG_USB_DEBUG */
>
> +#define FSG_NUM_BUFFERS_IS_VALID(num) (num >= 2 && num <= 4 ? true :
> false)
The “?:” is not needed.
#define FSG_NUM_BUFFERS_IS_VALID(num) ((num) >= 2 && (num) <= 4)
--
Best regards, _ _
.o. | Liege of Serenely Enlightened Majesty of o' \,=./ `o
..o | Computer Science, Michal "mina86" Nazarewicz (o o)
ooo +-----<email/xmpp: mnazarewicz@...gle.com>-----ooO--(_)--Ooo--
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