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Date: Fri, 12 Jan 2018 16:42:35 +0000
From: Oleksandr Shamray <oleksandrs@...lanox.com>
To: Florian Fainelli <f.fainelli@...il.com>,
"gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
"arnd@...db.de" <arnd@...db.de>
CC: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>,
"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
"openbmc@...ts.ozlabs.org" <openbmc@...ts.ozlabs.org>,
"joel@....id.au" <joel@....id.au>,
"jiri@...nulli.us" <jiri@...nulli.us>,
"tklauser@...tanz.ch" <tklauser@...tanz.ch>,
"linux-serial@...r.kernel.org" <linux-serial@...r.kernel.org>,
Vadim Pasternak <vadimp@...lanox.com>,
system-sw-low-level <system-sw-low-level@...lanox.com>,
"robh+dt@...nel.org" <robh+dt@...nel.org>,
"openocd-devel-owner@...ts.sourceforge.net"
<openocd-devel-owner@...ts.sourceforge.net>,
"linux-api@...r.kernel.org" <linux-api@...r.kernel.org>,
"davem@...emloft.net" <davem@...emloft.net>,
"mchehab@...nel.org" <mchehab@...nel.org>,
Jiri Pirko <jiri@...lanox.com>
Subject: RE: [patch v15 1/4] drivers: jtag: Add JTAG core driver
> -----Original Message-----
> From: Florian Fainelli [mailto:f.fainelli@...il.com]
> Sent: 26 декабря 2017 г. 1:09
> To: Oleksandr Shamray <oleksandrs@...lanox.com>;
> gregkh@...uxfoundation.org; arnd@...db.de
> Cc: linux-kernel@...r.kernel.org; linux-arm-kernel@...ts.infradead.org;
> devicetree@...r.kernel.org; openbmc@...ts.ozlabs.org; joel@....id.au;
> jiri@...nulli.us; tklauser@...tanz.ch; linux-serial@...r.kernel.org; Vadim
> Pasternak <vadimp@...lanox.com>; system-sw-low-level <system-sw-low-
> level@...lanox.com>; robh+dt@...nel.org; openocd-devel-
> owner@...ts.sourceforge.net; linux-api@...r.kernel.org;
> davem@...emloft.net; mchehab@...nel.org; Jiri Pirko
> <jiri@...lanox.com>
> Subject: Re: [patch v15 1/4] drivers: jtag: Add JTAG core driver
>
>
[snip]
> > +
> > + case JTAG_IOCXFER:
> > + if (copy_from_user(&xfer, (void *)arg,
> > + sizeof(struct jtag_xfer)))
> > + return -EFAULT;
> > +
> > + if (xfer.length >= JTAG_MAX_XFER_DATA_LEN)
> > + return -EINVAL;
> > +
> > + if (xfer.type > JTAG_SDR_XFER)
> > + return -EINVAL;
> > +
> > + if (xfer.direction > JTAG_WRITE_XFER)
> > + return -EINVAL;
> > +
> > + if (xfer.endstate > JTAG_STATE_PAUSEDR)
> > + return -EINVAL;
> > +
> > + data_size = DIV_ROUND_UP(xfer.length, BITS_PER_BYTE);
> > + xfer_data = memdup_user(u64_to_user_ptr(xfer.tdio),
> data_size);
> > +
> > + if (!xfer_data)
> > + return -EFAULT;
> > +
> > + if (jtag->ops->xfer) {
> > + err = jtag->ops->xfer(jtag, &xfer, xfer_data);
> > + } else {
> > + kfree(xfer_data);
> > + return -EOPNOTSUPP;
> > + }
>
> Why don't you move all of the code here into a function which will make the
> error handling consistent? Also, checking whether the jtag adapter
Greg KH <gregkh@...uxfoundation.org> Say to move all of this insight ioctl
> implements ops->xfer should probably be done before you do the
> memdup_user().
Yes
> > + if (err) {
> > + kfree(xfer_data);
> > + return -EFAULT;
> > + }
> > +
> > + if (jtag->ops->mode_set)
> > + err = jtag->ops->mode_set(jtag, value);
> > + else
> > + err = -EOPNOTSUPP;
> > + break;
>
> Same here, this can be checked before get_user().
>
Yes
> > + if (jtag->opened) {
> > + mutex_unlock(&jtag->open_lock);
> > + return -EINVAL;
>
> -EBUSY maybe?
>
Yes
> > +
> > + jtag = kzalloc(sizeof(*jtag) + round_up(priv_size,
> ARCH_DMA_MINALIGN),
> > + GFP_KERNEL);
> > + if (!jtag)
> > + return NULL;
>
> If you set ARCH_DMA_MINALIGN to 1 when not defined, what is this
> achieving that kmalloc() is not already doing?
>
Removed ARCH_DMA_MINALIGN
> > +
> > + jtag->ops = ops;
> > + return jtag;
> > +}
> > +EXPORT_SYMBOL_GPL(jtag_alloc);
> > +
> > +void jtag_free(struct jtag *jtag)
> > +{
> > + kfree(jtag);
> > +}
> > +EXPORT_SYMBOL_GPL(jtag_free);
> > +
> > +int jtag_register(struct jtag *jtag)
> > +{
> > + char *name;
> > + int err;
> > + int id;
> > +
> > + id = ida_simple_get(&jtag_ida, 0, 0, GFP_KERNEL);
> > + if (id < 0)
> > + return id;
> > +
> > + jtag->id = id;
> > +
> > + name = kzalloc(MAX_JTAG_NAME_LEN, GFP_KERNEL);
> > + if (!name) {
> > + err = -ENOMEM;
> > + goto err_jtag_alloc;
> > + }
>
> Can't you use jtag->miscdev.dev here to simplify the allocation error
> handling?
>
How, what you mean?
> > +#ifndef ARCH_DMA_MINALIGN
> > +#define ARCH_DMA_MINALIGN 1
> > +#endif
>
> Why?
>
Not used now, Deleted
> > +#endif /* __JTAG_H */
> > diff --git a/include/uapi/linux/jtag.h b/include/uapi/linux/jtag.h new
> > file mode 100644 index 0000000..cda2520
> > --- /dev/null
> > +++ b/include/uapi/linux/jtag.h
>
> [snip]
>
> > +struct jtag_xfer {
> > + __u8 type;
> > + __u8 direction;
>
> Can these two be an enum referring to what you defined earlier?
>
Greg KH <gregkh@...uxfoundation.org> say:
"All structures that cross the user/kernel boundry have to use the __ type variables.
No "unsigned char", it has to be "__u8", no "unsigned short", it has to be "__u16", and so on.
Also, watch out for your enumerated types, what's the packing end up looking like on these structures? Have you verified it works with a 64bit kernel and 32bit userspace all correctly?"
So I use __u8 type instead of enum to avoid errors while crossing 64bit kernel and 32bit userspace.
> > + __u8 endstate;
> > + __u32 length;
> > + __u64 tdio;
> > +};
> --
> Florian
Thaks.
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