On Fri, 2012-09-07 at 17:30 +0200, Paolo Bonzini wrote:
> In order to support zero-size allocation lengths, do not assert
> that we have a scatterlist until after checking cmd->data_length.
>
> But once we do this, we can have two cases of transport_kmap_data_sg
> returning NULL: a zero-size allocation length, or an out-of-memory
> condition. Report the latter using sense codes, so that the SCSI
> command that triggered it will fail.
>
> Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
> ---
Applied to master for-3.6.
Nice work Paolo!
> drivers/target/target_core_transport.c | 13 +++++++++----
> 1 files changed, 9 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
> index 2e55aa9..8facb74 100644
> --- a/drivers/target/target_core_transport.c
> +++ b/drivers/target/target_core_transport.c
> @@ -2185,7 +2185,6 @@ void *transport_kmap_data_sg(struct se_cmd *cmd)
> struct page **pages;
> int i;
>
> - BUG_ON(!sg);
> /*
> * We need to take into account a possible offset here for fabrics like
> * tcm_loop who may be using a contig buffer from the SCSI midlayer for
> @@ -2193,13 +2192,17 @@ void *transport_kmap_data_sg(struct se_cmd *cmd)
> */
> if (!cmd->t_data_nents)
> return NULL;
> - else if (cmd->t_data_nents == 1)
> +
> + BUG_ON(!sg);
> + if (cmd->t_data_nents == 1)
> return kmap(sg_page(sg)) + sg->offset;
>
> /* >1 page. use vmap */
> pages = kmalloc(sizeof(*pages) * cmd->t_data_nents, GFP_KERNEL);
> - if (!pages)
> + if (!pages) {
> + cmd->scsi_sense_reason = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
> return NULL;
> + }
>
> /* convert sg[] to pages[] */
> for_each_sg(cmd->t_data_sg, sg, cmd->t_data_nents, i) {
> @@ -2208,8 +2211,10 @@ void *transport_kmap_data_sg(struct se_cmd *cmd)
>
> cmd->t_data_vmap = vmap(pages, cmd->t_data_nents, VM_MAP, PAGE_KERNEL);
> kfree(pages);
> - if (!cmd->t_data_vmap)
> + if (!cmd->t_data_vmap) {
> + cmd->scsi_sense_reason = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
> return NULL;
> + }
>
> return cmd->t_data_vmap + cmd->t_data_sg[0].offset;
> }
--
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