Re: [PATCH v4 00/50] Remove the SCSI pointer from struct scsi_cmnd

Finn Thain
2022-02-18T00:45:37Z

Hi Bart,

On Wed, 16 Feb 2022, Bart Van Assche wrote:

> ...
> scsi: NCR5380: Introduce the NCR5380_cmd_priv() function
> scsi: NCR5380: Move the SCSI pointer to private command data

Please replace those two patches with the one below. This one is better
because it adds less source code, adds less scsi_cmnd private data,
updates an overlooked comment, avoids anything like "struct scsi_pointer"
and doesn't shadow any local variables.

From: Finn Thain <fthain@linux-m68k.org>
Subject: scsi: NCR5380: Add SCp members to struct NCR5380_cmd

This is necessary for the eventual removal of SCp from struct scsi_cmnd.

Cc: Michael Schmitz <schmitzmic@gmail.com>
Cc: Ondrej Zary <linux@zary.sk>
Suggested-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Finn Thain <fthain@linux-m68k.org>
---
drivers/scsi/NCR5380.c | 94 +++++++++++++++++++--------------------
drivers/scsi/NCR5380.h | 11 +++++
drivers/scsi/atari_scsi.c | 4 +-
drivers/scsi/g_NCR5380.c | 4 +-
drivers/scsi/mac_scsi.c | 7 +--
drivers/scsi/sun3_scsi.c | 2 +-
6 files changed, 66 insertions(+), 56 deletions(-)

diff --git a/drivers/scsi/NCR5380.c b/drivers/scsi/NCR5380.c
index 55af3e245a92..dece7d9eb4d3 100644
--- a/drivers/scsi/NCR5380.c
+++ b/drivers/scsi/NCR5380.c
@@ -84,8 +84,7 @@
* On command termination, the done function will be called as
* appropriate.
*
- * SCSI pointers are maintained in the SCp field of SCSI command
- * structures, being initialized after the command is connected
+ * The command data pointer is initialized after the command is connected
* in NCR5380_select, and set as appropriate in NCR5380_information_transfer.
* Note that in violation of the standard, an implicit SAVE POINTERS operation
* is done, since some BROKEN disks fail to issue an explicit SAVE POINTERS.
@@ -145,40 +144,38 @@ static void bus_reset_cleanup(struct Scsi_Host *);

static inline void initialize_SCp(struct scsi_cmnd *cmd)
{
- /*
- * Initialize the Scsi Pointer field so that all of the commands in the
- * various queues are valid.
- */
+ struct NCR5380_cmd *ncmd = NCR5380_to_ncmd(cmd);

if (scsi_bufflen(cmd)) {
- cmd->SCp.buffer = scsi_sglist(cmd);
- cmd->SCp.ptr = sg_virt(cmd->SCp.buffer);
- cmd->SCp.this_residual = cmd->SCp.buffer->length;
+ ncmd->buffer = scsi_sglist(cmd);
+ ncmd->ptr = sg_virt(ncmd->buffer);
+ ncmd->this_residual = ncmd->buffer->length;
} else {
- cmd->SCp.buffer = NULL;
- cmd->SCp.ptr = NULL;
- cmd->SCp.this_residual = 0;
+ ncmd->buffer = NULL;
+ ncmd->ptr = NULL;
+ ncmd->this_residual = 0;
}

- cmd->SCp.Status = 0;
- cmd->SCp.Message = 0;
+ ncmd->status = 0;
+ ncmd->message = 0;
}

-static inline void advance_sg_buffer(struct scsi_cmnd *cmd)
+static inline void advance_sg_buffer(struct NCR5380_cmd *ncmd)
{
- struct scatterlist *s = cmd->SCp.buffer;
+ struct scatterlist *s = ncmd->buffer;

- if (!cmd->SCp.this_residual && s && !sg_is_last(s)) {
- cmd->SCp.buffer = sg_next(s);
- cmd->SCp.ptr = sg_virt(cmd->SCp.buffer);
- cmd->SCp.this_residual = cmd->SCp.buffer->length;
+ if (!ncmd->this_residual && s && !sg_is_last(s)) {
+ ncmd->buffer = sg_next(s);
+ ncmd->ptr = sg_virt(ncmd->buffer);
+ ncmd->this_residual = ncmd->buffer->length;
}
}

static inline void set_resid_from_SCp(struct scsi_cmnd *cmd)
{
- int resid = cmd->SCp.this_residual;
- struct scatterlist *s = cmd->SCp.buffer;
+ struct NCR5380_cmd *ncmd = NCR5380_to_ncmd(cmd);
+ int resid = ncmd->this_residual;
+ struct scatterlist *s = ncmd->buffer;

if (s)
while (!sg_is_last(s)) {
@@ -564,7 +561,7 @@ static int NCR5380_queue_command(struct Scsi_Host *instance,
struct scsi_cmnd *cmd)
{
struct NCR5380_hostdata *hostdata = shost_priv(instance);
- struct NCR5380_cmd *ncmd = scsi_cmd_priv(cmd);
+ struct NCR5380_cmd *ncmd = NCR5380_to_ncmd(cmd);
unsigned long flags;

#if (NDEBUG & NDEBUG_NO_WRITE)
@@ -672,7 +669,7 @@ static struct scsi_cmnd *dequeue_next_cmd(struct Scsi_Host *instance)
static void requeue_cmd(struct Scsi_Host *instance, struct scsi_cmnd *cmd)
{
struct NCR5380_hostdata *hostdata = shost_priv(instance);
- struct NCR5380_cmd *ncmd = scsi_cmd_priv(cmd);
+ struct NCR5380_cmd *ncmd = NCR5380_to_ncmd(cmd);

if (hostdata->sensing == cmd) {
scsi_eh_restore_cmnd(cmd, &hostdata->ses);
@@ -757,6 +754,7 @@ static void NCR5380_main(struct work_struct *work)
static void NCR5380_dma_complete(struct Scsi_Host *instance)
{
struct NCR5380_hostdata *hostdata = shost_priv(instance);
+ struct NCR5380_cmd *ncmd = NCR5380_to_ncmd(hostdata->connected);
int transferred;
unsigned char **data;
int *count;
@@ -764,7 +762,7 @@ static void NCR5380_dma_complete(struct Scsi_Host *instance)
unsigned char p;

if (hostdata->read_overruns) {
- p = hostdata->connected->SCp.phase;
+ p = ncmd->phase;
if (p & SR_IO) {
udelay(10);
if ((NCR5380_read(BUS_AND_STATUS_REG) &
@@ -801,8 +799,8 @@ static void NCR5380_dma_complete(struct Scsi_Host *instance)
transferred = hostdata->dma_len - NCR5380_dma_residual(hostdata);
hostdata->dma_len = 0;

- data = (unsigned char **)&hostdata->connected->SCp.ptr;
- count = &hostdata->connected->SCp.this_residual;
+ data = (unsigned char **)&ncmd->ptr;
+ count = &ncmd->this_residual;
*data += transferred;
*count -= transferred;

@@ -1498,7 +1496,7 @@ static int NCR5380_transfer_dma(struct Scsi_Host *instance,
return -1;
}

- hostdata->connected->SCp.phase = p;
+ NCR5380_to_ncmd(hostdata->connected)->phase = p;

if (p & SR_IO) {
if (hostdata->read_overruns)
@@ -1690,7 +1688,7 @@ static void NCR5380_information_transfer(struct Scsi_Host *instance)
#endif

while ((cmd = hostdata->connected)) {
- struct NCR5380_cmd *ncmd = scsi_cmd_priv(cmd);
+ struct NCR5380_cmd *ncmd = NCR5380_to_ncmd(cmd);

tmp = NCR5380_read(STATUS_REG);
/* We only have a valid SCSI phase when REQ is asserted */
@@ -1705,17 +1703,17 @@ static void NCR5380_information_transfer(struct Scsi_Host *instance)
sun3_dma_setup_done != cmd) {
int count;

- advance_sg_buffer(cmd);
+ advance_sg_buffer(ncmd);

count = sun3scsi_dma_xfer_len(hostdata, cmd);

if (count > 0) {
if (cmd->sc_data_direction == DMA_TO_DEVICE)
sun3scsi_dma_send_setup(hostdata,
- cmd->SCp.ptr, count);
+ ncmd->ptr, count);
else
sun3scsi_dma_recv_setup(hostdata,
- cmd->SCp.ptr, count);
+ ncmd->ptr, count);
sun3_dma_setup_done = cmd;
}
#ifdef SUN3_SCSI_VME
@@ -1755,11 +1753,11 @@ static void NCR5380_information_transfer(struct Scsi_Host *instance)
* scatter-gather list, move onto the next one.
*/

- advance_sg_buffer(cmd);
+ advance_sg_buffer(ncmd);
dsprintk(NDEBUG_INFORMATION, instance,
"this residual %d, sg ents %d\n",
- cmd->SCp.this_residual,
- sg_nents(cmd->SCp.buffer));
+ ncmd->this_residual,
+ sg_nents(ncmd->buffer));

/*
* The preferred transfer method is going to be
@@ -1778,7 +1776,7 @@ static void NCR5380_information_transfer(struct Scsi_Host *instance)
if (transfersize > 0) {
len = transfersize;
if (NCR5380_transfer_dma(instance, &phase,
- &len, (unsigned char **)&cmd->SCp.ptr)) {
+ &len, (unsigned char **)&ncmd->ptr)) {
/*
* If the watchdog timer fires, all future
* accesses to this device will use the
@@ -1794,13 +1792,13 @@ static void NCR5380_information_transfer(struct Scsi_Host *instance)
/* Transfer a small chunk so that the
* irq mode lock is not held too long.
*/
- transfersize = min(cmd->SCp.this_residual,
+ transfersize = min(ncmd->this_residual,
NCR5380_PIO_CHUNK_SIZE);
len = transfersize;
NCR5380_transfer_pio(instance, &phase, &len,
- (unsigned char **)&cmd->SCp.ptr,
+ (unsigned char **)&ncmd->ptr,
0);
- cmd->SCp.this_residual -= transfersize - len;
+ ncmd->this_residual -= transfersize - len;
}
#ifdef CONFIG_SUN3
if (sun3_dma_setup_done == cmd)
@@ -1811,7 +1809,7 @@ static void NCR5380_information_transfer(struct Scsi_Host *instance)
len = 1;
data = &tmp;
NCR5380_transfer_pio(instance, &phase, &len, &data, 0);
- cmd->SCp.Message = tmp;
+ ncmd->message = tmp;

switch (tmp) {
case ABORT:
@@ -1828,15 +1826,15 @@ static void NCR5380_information_transfer(struct Scsi_Host *instance)
hostdata->connected = NULL;
hostdata->busy[scmd_id(cmd)] &= ~(1 << cmd->device->lun);

- set_status_byte(cmd, cmd->SCp.Status);
+ set_status_byte(cmd, ncmd->status);

set_resid_from_SCp(cmd);

if (cmd->cmnd[0] == REQUEST_SENSE)
complete_cmd(instance, cmd);
else {
- if (cmd->SCp.Status == SAM_STAT_CHECK_CONDITION ||
- cmd->SCp.Status == SAM_STAT_COMMAND_TERMINATED) {
+ if (ncmd->status == SAM_STAT_CHECK_CONDITION ||
+ ncmd->status == SAM_STAT_COMMAND_TERMINATED) {
dsprintk(NDEBUG_QUEUES, instance, "autosense: adding cmd %p to tail of autosense queue\n",
cmd);
list_add_tail(&ncmd->list,
@@ -2000,7 +1998,7 @@ static void NCR5380_information_transfer(struct Scsi_Host *instance)
len = 1;
data = &tmp;
NCR5380_transfer_pio(instance, &phase, &len, &data, 0);
- cmd->SCp.Status = tmp;
+ ncmd->status = tmp;
break;
default:
shost_printk(KERN_ERR, instance, "unknown phase\n");
@@ -2153,17 +2151,17 @@ static void NCR5380_reselect(struct Scsi_Host *instance)
if (sun3_dma_setup_done != tmp) {
int count;

- advance_sg_buffer(tmp);
+ advance_sg_buffer(ncmd);

count = sun3scsi_dma_xfer_len(hostdata, tmp);

if (count > 0) {
if (tmp->sc_data_direction == DMA_TO_DEVICE)
sun3scsi_dma_send_setup(hostdata,
- tmp->SCp.ptr, count);
+ ncmd->ptr, count);
else
sun3scsi_dma_recv_setup(hostdata,
- tmp->SCp.ptr, count);
+ ncmd->ptr, count);
sun3_dma_setup_done = tmp;
}
}
@@ -2206,7 +2204,7 @@ static bool list_del_cmd(struct list_head *haystack,
struct scsi_cmnd *needle)
{
if (list_find_cmd(haystack, needle)) {
- struct NCR5380_cmd *ncmd = scsi_cmd_priv(needle);
+ struct NCR5380_cmd *ncmd = NCR5380_to_ncmd(needle);

list_del(&ncmd->list);
return true;
diff --git a/drivers/scsi/NCR5380.h b/drivers/scsi/NCR5380.h
index 845bd2423e66..8dc2be4212dc 100644
--- a/drivers/scsi/NCR5380.h
+++ b/drivers/scsi/NCR5380.h
@@ -227,6 +227,12 @@ struct NCR5380_hostdata {
};

struct NCR5380_cmd {
+ char *ptr;
+ int this_residual;
+ struct scatterlist *buffer;
+ int status;
+ int message;
+ int phase;
struct list_head list;
};

@@ -240,6 +246,11 @@ static inline struct scsi_cmnd *NCR5380_to_scmd(struct NCR5380_cmd *ncmd_ptr)
return ((struct scsi_cmnd *)ncmd_ptr) - 1;
}

+static inline struct NCR5380_cmd *NCR5380_to_ncmd(struct scsi_cmnd *cmd)
+{
+ return scsi_cmd_priv(cmd);
+}
+
#ifndef NDEBUG
#define NDEBUG (0)
#endif
diff --git a/drivers/scsi/atari_scsi.c b/drivers/scsi/atari_scsi.c
index e9d0d99abc86..d401cf27113a 100644
--- a/drivers/scsi/atari_scsi.c
+++ b/drivers/scsi/atari_scsi.c
@@ -538,7 +538,7 @@ static int falcon_classify_cmd(struct scsi_cmnd *cmd)
static int atari_scsi_dma_xfer_len(struct NCR5380_hostdata *hostdata,
struct scsi_cmnd *cmd)
{
- int wanted_len = cmd->SCp.this_residual;
+ int wanted_len = NCR5380_to_ncmd(cmd)->this_residual;
int possible_len, limit;

if (wanted_len < DMA_MIN_SIZE)
@@ -610,7 +610,7 @@ static int atari_scsi_dma_xfer_len(struct NCR5380_hostdata *hostdata,
}

/* Last step: apply the hard limit on DMA transfers */
- limit = (atari_dma_buffer && !STRAM_ADDR(virt_to_phys(cmd->SCp.ptr))) ?
+ limit = (atari_dma_buffer && !STRAM_ADDR(virt_to_phys(NCR5380_to_ncmd(cmd)->ptr))) ?
STRAM_BUFFER_SIZE : 255*512;
if (possible_len > limit)
possible_len = limit;
diff --git a/drivers/scsi/g_NCR5380.c b/drivers/scsi/g_NCR5380.c
index 5923f86a384e..0c768e7d06b9 100644
--- a/drivers/scsi/g_NCR5380.c
+++ b/drivers/scsi/g_NCR5380.c
@@ -663,7 +663,7 @@ static inline int generic_NCR5380_psend(struct NCR5380_hostdata *hostdata,
static int generic_NCR5380_dma_xfer_len(struct NCR5380_hostdata *hostdata,
struct scsi_cmnd *cmd)
{
- int transfersize = cmd->SCp.this_residual;
+ int transfersize = NCR5380_to_ncmd(cmd)->this_residual;

if (hostdata->flags & FLAG_NO_PSEUDO_DMA)
return 0;
@@ -675,7 +675,7 @@ static int generic_NCR5380_dma_xfer_len(struct NCR5380_hostdata *hostdata,
/* Limit PDMA send to 512 B to avoid random corruption on DTC3181E */
if (hostdata->board == BOARD_DTC3181E &&
cmd->sc_data_direction == DMA_TO_DEVICE)
- transfersize = min(cmd->SCp.this_residual, 512);
+ transfersize = min(transfersize, 512);

return min(transfersize, DMA_MAX_SIZE);
}
diff --git a/drivers/scsi/mac_scsi.c b/drivers/scsi/mac_scsi.c
index 71d493a0bb43..2e511697fce3 100644
--- a/drivers/scsi/mac_scsi.c
+++ b/drivers/scsi/mac_scsi.c
@@ -404,11 +404,12 @@ static inline int macscsi_pwrite(struct NCR5380_hostdata *hostdata,
static int macscsi_dma_xfer_len(struct NCR5380_hostdata *hostdata,
struct scsi_cmnd *cmd)
{
- if (hostdata->flags & FLAG_NO_PSEUDO_DMA ||
- cmd->SCp.this_residual < setup_use_pdma)
+ int resid = NCR5380_to_ncmd(cmd)->this_residual;
+
+ if (hostdata->flags & FLAG_NO_PSEUDO_DMA || resid < setup_use_pdma)
return 0;

- return cmd->SCp.this_residual;
+ return resid;
}

static int macscsi_dma_residual(struct NCR5380_hostdata *hostdata)
diff --git a/drivers/scsi/sun3_scsi.c b/drivers/scsi/sun3_scsi.c
index 82a253270c3b..abf229b847a1 100644
--- a/drivers/scsi/sun3_scsi.c
+++ b/drivers/scsi/sun3_scsi.c
@@ -334,7 +334,7 @@ static int sun3scsi_dma_residual(struct NCR5380_hostdata *hostdata)
static int sun3scsi_dma_xfer_len(struct NCR5380_hostdata *hostdata,
struct scsi_cmnd *cmd)
{
- int wanted_len = cmd->SCp.this_residual;
+ int wanted_len = NCR5380_to_ncmd(cmd)->this_residual;

if (wanted_len < DMA_MIN_SIZE || blk_rq_is_passthrough(scsi_cmd_to_rq(cmd)))
return 0;
--
2.32.0