scsi: mpt3sas: Make MPI2_CONFIG_PAGE_IO_UNIT_8::Sensor[] a flexible array

This terminal 1-length variable array can be directly converted into a C99
flexible array member.

As all users of MPI2_CONFIG_PAGE_IO_UNIT_8 (Mpi2IOUnitPage8_t) do not use
Sensor[], no further source changes are required to accommodate its reduced
sizeof():

 - mpt3sas_config.c:mpt3sas_config_get_iounit_pg8() fetches a
   Mpi2IOUnitPage8_t into a caller-provided buffer, assuming
   sizeof(Mpi2IOUnitPage8_t) as the buffer size. It has one caller:

   - mpt3sas_base.c:_base_static_config_pages() passes the address of the
     Mpi2IOUnitPage8_t iounit_pg8 member of the per-adapter struct (struct
     MPT3SAS_ADAPTER *ioc) as the buffer. The assumed buffer size is
     therefore correct.

     However, the only subsequent use in mpt3sas of the thus populated
     ioc->iounit_pg8 is a little further on in the same function, and this
     use does not involve ioc->iounit_pg8.Sensor[].

     Note that iounit_pg8 occurs in the middle of the per-adapter struct,
     not at the end. The per-adapter struct is extensively used throughout
     mpt3sas even if its iounit_pg8 member isn't, resulting in an
     especially large amount of noise when comparing binary changes
     attributable to this commit.

Signed-off-by: James Seo <james@equiv.tech>
Link: https://lore.kernel.org/r/20230806170604.16143-3-james@equiv.tech
Tested-by: Borislav Petkov (AMD) <bp@alien8.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

diff --git a/drivers/scsi/mpt3sas/mpi/mpi2_cnfg.h b/drivers/scsi/mpt3sas/mpi/mpi2_cnfg.h
index 42d8201..12b656b 100644 (file)
--- a/drivers/scsi/mpt3sas/mpi/mpi2_cnfg.h
+++ b/drivers/scsi/mpt3sas/mpi/mpi2_cnfg.h
@@ -1200,12 +1200,9 @@ typedef struct _MPI2_IOUNIT8_SENSOR {
 #define MPI2_IOUNIT8_SENSOR_FLAGS_T0_ENABLE         (0x0001)
 
 /*
- *Host code (drivers, BIOS, utilities, etc.) should leave this define set to
- *one and check the value returned for NumSensors at runtime.
+ *Host code (drivers, BIOS, utilities, etc.) should check the value returned
+ *for NumSensors at runtime before using Sensor[].
  */
-#ifndef MPI2_IOUNITPAGE8_SENSOR_ENTRIES
-#define MPI2_IOUNITPAGE8_SENSOR_ENTRIES     (1)
-#endif
 
 typedef struct _MPI2_CONFIG_PAGE_IO_UNIT_8 {
        MPI2_CONFIG_PAGE_HEADER Header;                 /*0x00 */
@@ -1214,8 +1211,7 @@ typedef struct _MPI2_CONFIG_PAGE_IO_UNIT_8 {
        U8                      NumSensors;             /*0x0C */
        U8                      PollingInterval;        /*0x0D */
        U16                     Reserved3;              /*0x0E */
-       MPI2_IOUNIT8_SENSOR
-               Sensor[MPI2_IOUNITPAGE8_SENSOR_ENTRIES];/*0x10 */
+       MPI2_IOUNIT8_SENSOR     Sensor[];               /*0x10 */
 } MPI2_CONFIG_PAGE_IO_UNIT_8,
        *PTR_MPI2_CONFIG_PAGE_IO_UNIT_8,
        Mpi2IOUnitPage8_t, *pMpi2IOUnitPage8_t;