drivers/scsi/scsi_debug.c | 91 ++++++++++++++++++++++++--------------- 1 file changed, 57 insertions(+), 34 deletions(-)
Don't populate the read-only arrays on the stack at run time, instead
make them static const. Also reduces overall size.
before:
text data bss dec hex filename
367439 89582 5952 462973 7107d drivers/scsi/scsi_debug.o
after:
text data bss dec hex filename
365847 90702 5952 462501 70ea5 drivers/scsi/scsi_debug.o
(gcc 14.2.0, x86-64)
Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
---
drivers/scsi/scsi_debug.c | 91 ++++++++++++++++++++++++---------------
1 file changed, 57 insertions(+), 34 deletions(-)
diff --git a/drivers/scsi/scsi_debug.c b/drivers/scsi/scsi_debug.c
index 0847767d4d43..353cb60e1abe 100644
--- a/drivers/scsi/scsi_debug.c
+++ b/drivers/scsi/scsi_debug.c
@@ -2674,8 +2674,10 @@ static int resp_rsup_tmfs(struct scsi_cmnd *scp,
static int resp_err_recov_pg(unsigned char *p, int pcontrol, int target)
{ /* Read-Write Error Recovery page for mode_sense */
- unsigned char err_recov_pg[] = {0x1, 0xa, 0xc0, 11, 240, 0, 0, 0,
- 5, 0, 0xff, 0xff};
+ static const unsigned char err_recov_pg[] = {
+ 0x1, 0xa, 0xc0, 11, 240, 0, 0, 0,
+ 5, 0, 0xff, 0xff
+ };
memcpy(p, err_recov_pg, sizeof(err_recov_pg));
if (1 == pcontrol)
@@ -2685,8 +2687,10 @@ static int resp_err_recov_pg(unsigned char *p, int pcontrol, int target)
static int resp_disconnect_pg(unsigned char *p, int pcontrol, int target)
{ /* Disconnect-Reconnect page for mode_sense */
- unsigned char disconnect_pg[] = {0x2, 0xe, 128, 128, 0, 10, 0, 0,
- 0, 0, 0, 0, 0, 0, 0, 0};
+ static const unsigned char disconnect_pg[] = {
+ 0x2, 0xe, 128, 128, 0, 10, 0, 0,
+ 0, 0, 0, 0, 0, 0, 0, 0
+ };
memcpy(p, disconnect_pg, sizeof(disconnect_pg));
if (1 == pcontrol)
@@ -2696,9 +2700,11 @@ static int resp_disconnect_pg(unsigned char *p, int pcontrol, int target)
static int resp_format_pg(unsigned char *p, int pcontrol, int target)
{ /* Format device page for mode_sense */
- unsigned char format_pg[] = {0x3, 0x16, 0, 0, 0, 0, 0, 0,
- 0, 0, 0, 0, 0, 0, 0, 0,
- 0, 0, 0, 0, 0x40, 0, 0, 0};
+ static const unsigned char format_pg[] = {
+ 0x3, 0x16, 0, 0, 0, 0, 0, 0,
+ 0, 0, 0, 0, 0, 0, 0, 0,
+ 0, 0, 0, 0, 0x40, 0, 0, 0
+ };
memcpy(p, format_pg, sizeof(format_pg));
put_unaligned_be16(sdebug_sectors_per, p + 10);
@@ -2716,10 +2722,14 @@ static unsigned char caching_pg[] = {0x8, 18, 0x14, 0, 0xff, 0xff, 0, 0,
static int resp_caching_pg(unsigned char *p, int pcontrol, int target)
{ /* Caching page for mode_sense */
- unsigned char ch_caching_pg[] = {/* 0x8, 18, */ 0x4, 0, 0, 0, 0, 0,
- 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
- unsigned char d_caching_pg[] = {0x8, 18, 0x14, 0, 0xff, 0xff, 0, 0,
- 0xff, 0xff, 0xff, 0xff, 0x80, 0x14, 0, 0, 0, 0, 0, 0};
+ static const unsigned char ch_caching_pg[] = {
+ /* 0x8, 18, */ 0x4, 0, 0, 0, 0, 0,
+ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
+ };
+ static const unsigned char d_caching_pg[] = {
+ 0x8, 18, 0x14, 0, 0xff, 0xff, 0, 0,
+ 0xff, 0xff, 0xff, 0xff, 0x80, 0x14, 0, 0, 0, 0, 0, 0
+ };
if (SDEBUG_OPT_N_WCE & sdebug_opts)
caching_pg[2] &= ~0x4; /* set WCE=0 (default WCE=1) */
@@ -2738,8 +2748,10 @@ static int resp_ctrl_m_pg(unsigned char *p, int pcontrol, int target)
{ /* Control mode page for mode_sense */
unsigned char ch_ctrl_m_pg[] = {/* 0xa, 10, */ 0x6, 0, 0, 0, 0, 0,
0, 0, 0, 0};
- unsigned char d_ctrl_m_pg[] = {0xa, 10, 2, 0, 0, 0, 0, 0,
- 0, 0, 0x2, 0x4b};
+ static const unsigned char d_ctrl_m_pg[] = {
+ 0xa, 10, 2, 0, 0, 0, 0, 0,
+ 0, 0, 0x2, 0x4b
+ };
if (sdebug_dsense)
ctrl_m_pg[2] |= 0x4;
@@ -2794,10 +2806,14 @@ static int resp_grouping_m_pg(unsigned char *p, int pcontrol, int target)
static int resp_iec_m_pg(unsigned char *p, int pcontrol, int target)
{ /* Informational Exceptions control mode page for mode_sense */
- unsigned char ch_iec_m_pg[] = {/* 0x1c, 0xa, */ 0x4, 0xf, 0, 0, 0, 0,
- 0, 0, 0x0, 0x0};
- unsigned char d_iec_m_pg[] = {0x1c, 0xa, 0x08, 0, 0, 0, 0, 0,
- 0, 0, 0x0, 0x0};
+ static const unsigned char ch_iec_m_pg[] = {
+ /* 0x1c, 0xa, */ 0x4, 0xf, 0, 0, 0, 0,
+ 0, 0, 0x0, 0x0
+ };
+ static const unsigned char d_iec_m_pg[] = {
+ 0x1c, 0xa, 0x08, 0, 0, 0, 0, 0,
+ 0, 0, 0x0, 0x0
+ };
memcpy(p, iec_m_pg, sizeof(iec_m_pg));
if (1 == pcontrol)
@@ -2809,8 +2825,9 @@ static int resp_iec_m_pg(unsigned char *p, int pcontrol, int target)
static int resp_sas_sf_m_pg(unsigned char *p, int pcontrol, int target)
{ /* SAS SSP mode page - short format for mode_sense */
- unsigned char sas_sf_m_pg[] = {0x19, 0x6,
- 0x6, 0x0, 0x7, 0xd0, 0x0, 0x0};
+ static const unsigned char sas_sf_m_pg[] = {
+ 0x19, 0x6, 0x6, 0x0, 0x7, 0xd0, 0x0, 0x0
+ };
memcpy(p, sas_sf_m_pg, sizeof(sas_sf_m_pg));
if (1 == pcontrol)
@@ -2854,9 +2871,10 @@ static int resp_sas_pcd_m_spg(unsigned char *p, int pcontrol, int target,
static int resp_sas_sha_m_spg(unsigned char *p, int pcontrol)
{ /* SAS SSP shared protocol specific port mode subpage */
- unsigned char sas_sha_m_pg[] = {0x59, 0x2, 0, 0xc, 0, 0x6, 0x10, 0,
- 0, 0, 0, 0, 0, 0, 0, 0,
- };
+ static const unsigned char sas_sha_m_pg[] = {
+ 0x59, 0x2, 0, 0xc, 0, 0x6, 0x10, 0,
+ 0, 0, 0, 0, 0, 0, 0, 0,
+ };
memcpy(p, sas_sha_m_pg, sizeof(sas_sha_m_pg));
if (1 == pcontrol)
@@ -2923,8 +2941,10 @@ static int process_medium_part_m_pg(struct sdebug_dev_info *devip,
static int resp_compression_m_pg(unsigned char *p, int pcontrol, int target,
unsigned char dce)
{ /* Compression page for mode_sense (tape) */
- unsigned char compression_pg[] = {0x0f, 14, 0x40, 0, 0, 0, 0, 0,
- 0, 0, 0, 0, 00, 00};
+ static const unsigned char compression_pg[] = {
+ 0x0f, 14, 0x40, 0, 0, 0, 0, 0,
+ 0, 0, 0, 0, 0, 0
+ };
memcpy(p, compression_pg, sizeof(compression_pg));
if (dce)
@@ -3282,9 +3302,10 @@ static int resp_mode_select(struct scsi_cmnd *scp,
static int resp_temp_l_pg(unsigned char *arr)
{
- unsigned char temp_l_pg[] = {0x0, 0x0, 0x3, 0x2, 0x0, 38,
- 0x0, 0x1, 0x3, 0x2, 0x0, 65,
- };
+ static const unsigned char temp_l_pg[] = {
+ 0x0, 0x0, 0x3, 0x2, 0x0, 38,
+ 0x0, 0x1, 0x3, 0x2, 0x0, 65,
+ };
memcpy(arr, temp_l_pg, sizeof(temp_l_pg));
return sizeof(temp_l_pg);
@@ -3292,8 +3313,9 @@ static int resp_temp_l_pg(unsigned char *arr)
static int resp_ie_l_pg(unsigned char *arr)
{
- unsigned char ie_l_pg[] = {0x0, 0x0, 0x3, 0x3, 0x0, 0x0, 38,
- };
+ static const unsigned char ie_l_pg[] = {
+ 0x0, 0x0, 0x3, 0x3, 0x0, 0x0, 38,
+ };
memcpy(arr, ie_l_pg, sizeof(ie_l_pg));
if (iec_m_pg[2] & 0x4) { /* TEST bit set */
@@ -3305,11 +3327,12 @@ static int resp_ie_l_pg(unsigned char *arr)
static int resp_env_rep_l_spg(unsigned char *arr)
{
- unsigned char env_rep_l_spg[] = {0x0, 0x0, 0x23, 0x8,
- 0x0, 40, 72, 0xff, 45, 18, 0, 0,
- 0x1, 0x0, 0x23, 0x8,
- 0x0, 55, 72, 35, 55, 45, 0, 0,
- };
+ static const unsigned char env_rep_l_spg[] = {
+ 0x0, 0x0, 0x23, 0x8,
+ 0x0, 40, 72, 0xff, 45, 18, 0, 0,
+ 0x1, 0x0, 0x23, 0x8,
+ 0x0, 55, 72, 35, 55, 45, 0, 0,
+ };
memcpy(arr, env_rep_l_spg, sizeof(env_rep_l_spg));
return sizeof(env_rep_l_spg);
--
2.50.0On Tue, 29 Jul 2025 07:49:30 +0100, Colin Ian King wrote:
> Don't populate the read-only arrays on the stack at run time, instead
> make them static const. Also reduces overall size.
>
> before:
> text data bss dec hex filename
> 367439 89582 5952 462973 7107d drivers/scsi/scsi_debug.o
>
> [...]
Applied to 6.17/scsi-queue, thanks!
[1/1] scsi: scsi_debug: make read-only arrays static const
https://git.kernel.org/mkp/scsi/c/383cd6d879a1
--
Martin K. Petersen Oracle Linux Engineering
Colin, > Don't populate the read-only arrays on the stack at run time, instead > make them static const. Also reduces overall size. Applied to 6.17/scsi-staging, thanks! -- Martin K. Petersen
Le 29/07/2025 à 08:49, Colin Ian King a écrit : > Don't populate the read-only arrays on the stack at run time, instead > make them static const. Also reduces overall size. > > before: > text data bss dec hex filename > 367439 89582 5952 462973 7107d drivers/scsi/scsi_debug.o > > after: > text data bss dec hex filename > 365847 90702 5952 462501 70ea5 drivers/scsi/scsi_debug.o Hi, out of curiosity, any idea why 'data' increase? All my constification patches lead to data reduction. > > (gcc 14.2.0, x86-64) (same kind of behavior with 15.1.1) CJ
On 29/07/2025 18:45, Christophe JAILLET wrote: > Le 29/07/2025 à 08:49, Colin Ian King a écrit : >> Don't populate the read-only arrays on the stack at run time, instead >> make them static const. Also reduces overall size. >> >> before: >> text data bss dec hex filename >> 367439 89582 5952 462973 7107d drivers/scsi/ >> scsi_debug.o >> >> after: >> text data bss dec hex filename >> 365847 90702 5952 462501 70ea5 drivers/scsi/ >> scsi_debug.o > > Hi, > > out of curiosity, any idea why 'data' increase? Because the arrays are being stored in the data section rather than on the stack. > > All my constification patches lead to data reduction. > >> >> (gcc 14.2.0, x86-64) > > (same kind of behavior with 15.1.1) > > > CJ
Le 29/07/2025 à 21:49, Colin King (gmail) a écrit : > On 29/07/2025 18:45, Christophe JAILLET wrote: >> Le 29/07/2025 à 08:49, Colin Ian King a écrit : >>> Don't populate the read-only arrays on the stack at run time, instead >>> make them static const. Also reduces overall size. >>> >>> before: >>> text data bss dec hex filename >>> 367439 89582 5952 462973 7107d drivers/scsi/ >>> scsi_debug.o >>> >>> after: >>> text data bss dec hex filename >>> 365847 90702 5952 462501 70ea5 drivers/scsi/ >>> scsi_debug.o >> >> Hi, >> >> out of curiosity, any idea why 'data' increase? > > Because the arrays are being stored in the data section rather than on > the stack. Even when const is used? See [1] for example, adding const moves the size from data to text. I would expect the same with your patch. CJ [1]: https://web.git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?id=86b0fc4b2b45a78cbdc11873bc596d140eff390c > >> >> All my constification patches lead to data reduction. >> >>> >>> (gcc 14.2.0, x86-64) >> >> (same kind of behavior with 15.1.1) >> >> >> CJ >
On 7/28/25 11:49 PM, Colin Ian King wrote: > Don't populate the read-only arrays on the stack at run time, instead > make them static const. Also reduces overall size. Reviewed-by: Bart Van Assche <bvanassche@acm.org>
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