Re: [PATCH 8/9] scsi: megaraid_sas - Add the IEEE SGL support to the driver

Andrew Morton
2009-02-19T00:38:52Z

On Tue, 17 Feb 2009 10:31:10 -0700
"Yang, Bo" <Bo.Yang@lsi.com> wrote:

> Add the IEEE SGL support to MegaRAID SAS driver
>
> Signed-off-by Bo Yang<bo.yang@lsi.com>
>
> ---
> drivers/scsi/megaraid/megaraid_sas.c | 125 ++++++++++++++++++++++++++---------
> drivers/scsi/megaraid/megaraid_sas.h | 13 +++
> 2 files changed, 107 insertions(+), 31 deletions(-)
>
> diff -rupN linux-2.6.28_orig/drivers/scsi/megaraid/megaraid_sas.c linux-2.6.28_new/drivers/scsi/megaraid/megaraid_sas.c
> --- linux-2.6.28_orig/drivers/scsi/megaraid/megaraid_sas.c 2009-02-12 16:36:41.000000000 -0500
> +++ linux-2.6.28_new/drivers/scsi/megaraid/megaraid_sas.c 2009-02-12 17:24:26.000000000 -0500
> @@ -698,6 +698,35 @@ megasas_make_sgl64(struct megasas_instan
> return sge_count;
> }
>
> +/**
> + * megasas_make_sgl64 - Prepares 64-bit SGL
> + * @instance: Adapter soft state
> + * @scp: SCSI command from the mid-layer
> + * @mfi_sgl: SGL to be filled in
> + *
> + * If successful, this function returns the number of SG elements. Otherwise,
> + * it returnes -1.
> + */
> +static int
> +megasas_make_sgl_skinny(struct megasas_instance *instance,
> + struct scsi_cmnd *scp, union megasas_sgl *mfi_sgl)
> +{
> + int i;
> + int sge_count;
> + struct scatterlist *os_sgl;
> +
> + sge_count = scsi_dma_map(scp);
> + BUG_ON(sge_count < 0);

Crashing the kernel if scsi_dma_map() fails seems inappropriate?

> + if (sge_count) {
> + scsi_for_each_sg(scp, os_sgl, sge_count, i) {
> + mfi_sgl->sge_skinny[i].length = sg_dma_len(os_sgl);
> + mfi_sgl->sge_skinny[i].phys_addr = sg_dma_address(os_sgl);
> + }
> + }
> + return sge_count;
> +}
>
> ...
>
> + if (instance->flag_ieee == 1) {
> + flags = MFI_FRAME_IEEE;
> + }

We typically omit the unneeded brakes in this situation. But there are
a huge number of places in this driver which ignored that convention.

> /*
> * The RAID firmware may require extended timeouts.
> @@ -1405,7 +1476,7 @@ megasas_bios_param(struct scsi_device *s
> return 0;
> }
>
> -static void megasas_aen_polling(void *arg);
> +static void megasas_aen_polling(struct work_struct *work);
>
> /**
> * megasas_service_aen - Processes an event notification
> @@ -1433,7 +1504,8 @@ megasas_service_aen(struct megasas_insta
> } else {
> ev->instance = instance;
> INIT_WORK(&ev->hotplug_work, megasas_aen_polling);
> - schedule_delayed_work(&ev->hotplug_work, 0);
> + schedule_delayed_work(
> + (struct delayed_work *)&ev->hotplug_work, 0);

Why was this cast added? It looks either unneeded or wrong.

> @@ -4043,12 +4108,12 @@ megasas_aen_polling(struct work_struct *
> class_locale.members.locale = MR_EVT_LOCALE_ALL;
> class_locale.members.class = MR_EVT_CLASS_DEBUG;
>
> - down(&instance->aen_mutex);
> + mutex_lock(&instance->aen_mutex);
>
> error = megasas_register_aen(instance, seq_num,
> class_locale.word);
>
> - up(&instance->aen_mutex);
> + mutex_unlock(&instance->aen_mutex);

OK, so this fixes a bug which was added in an earlier patch.

Please just fix the original patch so that we don't introduce bisection
holes.

> if (error)
> printk(KERN_ERR "%s[%d]: register aen failed error %x\n",
> diff -rupN linux-2.6.28_orig/drivers/scsi/megaraid/megaraid_sas.h linux-2.6.28_new/drivers/scsi/megaraid/megaraid_sas.h
> --- linux-2.6.28_orig/drivers/scsi/megaraid/megaraid_sas.h 2009-02-12 16:36:42.000000000 -0500
> +++ linux-2.6.28_new/drivers/scsi/megaraid/megaraid_sas.h 2009-02-12 16:53:50.000000000 -0500
> @@ -96,6 +96,7 @@
> #define MFI_FRAME_DIR_WRITE 0x0008
> #define MFI_FRAME_DIR_READ 0x0010
> #define MFI_FRAME_DIR_BOTH 0x0018
> +#define MFI_FRAME_IEEE 0x0020
>
> /*
> * Definition for cmd_status
> @@ -752,10 +753,19 @@ struct megasas_sge64 {
>
> } __attribute__ ((packed));
>
> +struct megasas_sge_skinny {
> +
> + u64 phys_addr;
> + u32 length;
> + u32 flag;
> +
> +} __attribute__ ((packed));

Please use __packed throughout the driver. (might be a problem if this
header is supposed to be shared with userspace?)