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scsi: storvsc: Don't assume that the scatterlist is not chained
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The current code assumes that the scatterlists presented are not chained.
Fix the code to not make this assumption.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Reviewed-by: Long Li <longli@microsoft.com>
Signed-off-by: James Bottomley <JBottomley@Odin.com>
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K. Y. Srinivasan authored and James Bottomley committed Apr 9, 2015
1 parent 8de5807 commit aaced99
Showing 1 changed file with 57 additions and 42 deletions.
99 changes: 57 additions & 42 deletions drivers/scsi/storvsc_drv.c
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Original file line number Diff line number Diff line change
Expand Up @@ -626,19 +626,6 @@ static struct scatterlist *create_bounce_buffer(struct scatterlist *sgl,
return NULL;
}

/* Disgusting wrapper functions */
static inline unsigned long sg_kmap_atomic(struct scatterlist *sgl, int idx)
{
void *addr = kmap_atomic(sg_page(sgl + idx));
return (unsigned long)addr;
}

static inline void sg_kunmap_atomic(unsigned long addr)
{
kunmap_atomic((void *)addr);
}


/* Assume the original sgl has enough room */
static unsigned int copy_from_bounce_buffer(struct scatterlist *orig_sgl,
struct scatterlist *bounce_sgl,
Expand All @@ -653,32 +640,38 @@ static unsigned int copy_from_bounce_buffer(struct scatterlist *orig_sgl,
unsigned long bounce_addr = 0;
unsigned long dest_addr = 0;
unsigned long flags;
struct scatterlist *cur_dest_sgl;
struct scatterlist *cur_src_sgl;

local_irq_save(flags);

cur_dest_sgl = orig_sgl;
cur_src_sgl = bounce_sgl;
for (i = 0; i < orig_sgl_count; i++) {
dest_addr = sg_kmap_atomic(orig_sgl,i) + orig_sgl[i].offset;
dest_addr = (unsigned long)
kmap_atomic(sg_page(cur_dest_sgl)) +
cur_dest_sgl->offset;
dest = dest_addr;
destlen = orig_sgl[i].length;
destlen = cur_dest_sgl->length;

if (bounce_addr == 0)
bounce_addr = sg_kmap_atomic(bounce_sgl,j);
bounce_addr = (unsigned long)kmap_atomic(
sg_page(cur_src_sgl));

while (destlen) {
src = bounce_addr + bounce_sgl[j].offset;
srclen = bounce_sgl[j].length - bounce_sgl[j].offset;
src = bounce_addr + cur_src_sgl->offset;
srclen = cur_src_sgl->length - cur_src_sgl->offset;

copylen = min(srclen, destlen);
memcpy((void *)dest, (void *)src, copylen);

total_copied += copylen;
bounce_sgl[j].offset += copylen;
cur_src_sgl->offset += copylen;
destlen -= copylen;
dest += copylen;

if (bounce_sgl[j].offset == bounce_sgl[j].length) {
if (cur_src_sgl->offset == cur_src_sgl->length) {
/* full */
sg_kunmap_atomic(bounce_addr);
kunmap_atomic((void *)bounce_addr);
j++;

/*
Expand All @@ -692,21 +685,27 @@ static unsigned int copy_from_bounce_buffer(struct scatterlist *orig_sgl,
/*
* We are done; cleanup and return.
*/
sg_kunmap_atomic(dest_addr - orig_sgl[i].offset);
kunmap_atomic((void *)(dest_addr -
cur_dest_sgl->offset));
local_irq_restore(flags);
return total_copied;
}

/* if we need to use another bounce buffer */
if (destlen || i != orig_sgl_count - 1)
bounce_addr = sg_kmap_atomic(bounce_sgl,j);
if (destlen || i != orig_sgl_count - 1) {
cur_src_sgl = sg_next(cur_src_sgl);
bounce_addr = (unsigned long)
kmap_atomic(
sg_page(cur_src_sgl));
}
} else if (destlen == 0 && i == orig_sgl_count - 1) {
/* unmap the last bounce that is < PAGE_SIZE */
sg_kunmap_atomic(bounce_addr);
kunmap_atomic((void *)bounce_addr);
}
}

sg_kunmap_atomic(dest_addr - orig_sgl[i].offset);
kunmap_atomic((void *)(dest_addr - cur_dest_sgl->offset));
cur_dest_sgl = sg_next(cur_dest_sgl);
}

local_irq_restore(flags);
Expand All @@ -727,48 +726,61 @@ static unsigned int copy_to_bounce_buffer(struct scatterlist *orig_sgl,
unsigned long bounce_addr = 0;
unsigned long src_addr = 0;
unsigned long flags;
struct scatterlist *cur_src_sgl;
struct scatterlist *cur_dest_sgl;

local_irq_save(flags);

cur_src_sgl = orig_sgl;
cur_dest_sgl = bounce_sgl;

for (i = 0; i < orig_sgl_count; i++) {
src_addr = sg_kmap_atomic(orig_sgl,i) + orig_sgl[i].offset;
src_addr = (unsigned long)
kmap_atomic(sg_page(cur_src_sgl)) +
cur_src_sgl->offset;
src = src_addr;
srclen = orig_sgl[i].length;
srclen = cur_src_sgl->length;

if (bounce_addr == 0)
bounce_addr = sg_kmap_atomic(bounce_sgl,j);
bounce_addr = (unsigned long)
kmap_atomic(sg_page(cur_dest_sgl));

while (srclen) {
/* assume bounce offset always == 0 */
dest = bounce_addr + bounce_sgl[j].length;
destlen = PAGE_SIZE - bounce_sgl[j].length;
dest = bounce_addr + cur_dest_sgl->length;
destlen = PAGE_SIZE - cur_dest_sgl->length;

copylen = min(srclen, destlen);
memcpy((void *)dest, (void *)src, copylen);

total_copied += copylen;
bounce_sgl[j].length += copylen;
cur_dest_sgl->length += copylen;
srclen -= copylen;
src += copylen;

if (bounce_sgl[j].length == PAGE_SIZE) {
if (cur_dest_sgl->length == PAGE_SIZE) {
/* full..move to next entry */
sg_kunmap_atomic(bounce_addr);
kunmap_atomic((void *)bounce_addr);
bounce_addr = 0;
j++;
}

/* if we need to use another bounce buffer */
if (srclen && bounce_addr == 0)
bounce_addr = sg_kmap_atomic(bounce_sgl, j);
if (srclen && bounce_addr == 0) {
cur_dest_sgl = sg_next(cur_dest_sgl);
bounce_addr = (unsigned long)
kmap_atomic(
sg_page(cur_dest_sgl));
}

}

sg_kunmap_atomic(src_addr - orig_sgl[i].offset);
kunmap_atomic((void *)(src_addr - cur_src_sgl->offset));
cur_src_sgl = sg_next(cur_src_sgl);
}

if (bounce_addr)
sg_kunmap_atomic(bounce_addr);
kunmap_atomic((void *)bounce_addr);

local_irq_restore(flags);

Expand Down Expand Up @@ -1536,6 +1548,7 @@ static int storvsc_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *scmnd)
struct scatterlist *sgl;
unsigned int sg_count = 0;
struct vmscsi_request *vm_srb;
struct scatterlist *cur_sgl;

if (vmstor_current_major <= VMSTOR_WIN8_MAJOR) {
/*
Expand Down Expand Up @@ -1617,10 +1630,12 @@ static int storvsc_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *scmnd)
}

cmd_request->data_buffer.offset = sgl[0].offset;

for (i = 0; i < sg_count; i++)
cur_sgl = sgl;
for (i = 0; i < sg_count; i++) {
cmd_request->data_buffer.pfn_array[i] =
page_to_pfn(sg_page((&sgl[i])));
page_to_pfn(sg_page((cur_sgl)));
cur_sgl = sg_next(cur_sgl);
}

} else if (scsi_sglist(scmnd)) {
cmd_request->data_buffer.offset =
Expand Down

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