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SubjectRE: [PATCH V3 1/1] Drivers: hv: Implement the file copy service
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> -----Original Message-----
> From: Levente Kurusa [mailto:ilevex.linux@gmail.com] On Behalf Of Levente
> Kurusa
> Sent: Tuesday, January 21, 2014 11:01 AM
> To: KY Srinivasan; gregkh@linuxfoundation.org; linux-kernel@vger.kernel.org;
> devel@linuxdriverproject.org; olaf@aepfle.de; apw@canonical.com;
> jasowang@redhat.com
> Subject: Re: [PATCH V3 1/1] Drivers: hv: Implement the file copy service
>
> Hello,
>
> On 01/21/2014 08:06 PM, K. Y. Srinivasan wrote:
> > Implement the file copy service for Linux guests on Hyper-V. This permits the
> > host to copy a file (over VMBUS) into the guest. This facility is part of
> > "guest integration services" supported on the Windows platform.
> > Here is a link that provides additional details on this functionality:
> >
> > http://technet.microsoft.com/en-us/library/dn464282.aspx
> >
> > In V1 version of the patch I have addressed comments from
> > Olaf Hering <olaf@aepfle.de> and Dan Carpenter
> <dan.carpenter@oracle.com>
> >
> > In V2 version of this patch I did some minor cleanup (making some globals
> > static). In this version of the patch I have addressed all of Olaf's
> > most recent set of comments/concerns.
> >
> > Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
> > ---
>
> Just a few comments.
>
> > + /*
> > + * The strings sent from the host are encoded in
> > + * in utf16; convert it to utf8 strings.
> > + * The host assures us that the utf16 strings will not exceed
> > + * the max lengths specified. We will however, reserve room
> > + * for the string terminating character - in the utf16s_utf8s()
> > + * function we limit the size of the buffer where the converted
> > + * string is placed to W_MAX_PATH -1 to gaurantee
>
> s/gaurantee/guarantee
I will fix this.
>
> > + * that the strings can be properly terminated!
> > + */
> > +
> > + switch (operation) {
> > + case START_FILE_COPY:
> > + memset(smsg_out, 0, sizeof(struct hv_start_fcopy));
> > + smsg_out->hdr.operation = operation;
> > + smsg_in = (struct hv_start_fcopy
> *)fcopy_transaction.fcopy_msg;
> > +
> > + utf16s_to_utf8s((wchar_t *)smsg_in->file_name,
> W_MAX_PATH,
> > + UTF16_LITTLE_ENDIAN,
> > + (__u8 *)smsg_out->file_name, W_MAX_PATH -
> 1);
> > +
> > + utf16s_to_utf8s((wchar_t *)smsg_in->path_name,
> W_MAX_PATH,
> > + UTF16_LITTLE_ENDIAN,
> > + (__u8 *)smsg_out->path_name, W_MAX_PATH -
> 1);
> > +
> > + smsg_out->copy_flags = smsg_in->copy_flags;
> > + smsg_out->file_size = smsg_in->file_size;
> > + break;
> > +
> > + default:
> > + break;
> > + }
> > + up(&fcopy_transaction.read_sema);
> > + return;
> > +}
> > +
> > [...]
> > +static ssize_t fcopy_read(struct file *file, char __user *buf,
> > + size_t count, loff_t *ppos)
> > +{
> > + int ret;
> > + void *src;
> > + size_t copy_size;
> > + int operation;
> > +
> > + /*
> > + * Wait until there is something to be read.
> > + */
> > + ret = down_interruptible(&fcopy_transaction.read_sema);
> > + if (ret)
> > + return -EINTR;
>
> I don't know, but since you use 'ret' only once and you don't
> even read it after, you could just simply remove it and check
> the return code of down_interruptible() directly

Good point; I will fix this.

Thank you,

K. Y


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