From 761e3bd9f5e3aafa95ad3ae50a637dc67c8774f0 Mon Sep 17 00:00:00 2001

From: NeilBrown <neilb@suse.de>

Date: Thu, 31 Oct 2019 15:15:38 +1100

Subject: [RHEL7.8 PATCH V2 47/47] super-intel: don't mark structs 'packed'

 unnecessarily

super-intel marks a number of structures 'packed', but this

doesn't change the layout - they are already well organized.

This is a problem a gcc warns when code takes the address

of a field in a packet struct - as super-intel sometimes does.

So remove the marking where isn't needed.

Do ensure this does introduce a regression, add a compile-time

assertion that the size of the structure is exactly the value

it had before the 'packed' notation was removed.

Note that a couple of structure do need to be packed.

As the address of fields is never taken, that is safe.

Signed-off-by: NeilBrown <neilb@suse.de>

Acked-by: Artur Paszkiewicz <artur.paszkiewicz@intel.com>

Signed-off-by: Jes Sorensen <jsorensen@fb.com>

---

 super-intel.c | 32 ++++++++++++++++++++++++++------

 1 file changed, 26 insertions(+), 6 deletions(-)

diff --git a/super-intel.c b/super-intel.c

index 713058c..a7fbed4 100644

--- a/super-intel.c

+++ b/super-intel.c

@@ -96,6 +96,19 @@

 						   * mutliple PPL area

 						   */

+/*

+ * This macro let's us ensure that no-one accidentally

+ * changes the size of a struct

+ */

+#define ASSERT_SIZE(_struct, size) \

+static inline void __assert_size_##_struct(void)	\

+{							\

+	switch (0) {					\

+	case 0: break;					\

+	case (sizeof(struct _struct) == size): break;	\

+	}						\

+}

+

 /* Disk configuration info. */

 #define IMSM_MAX_DEVICES 255

 struct imsm_disk {

@@ -112,6 +125,7 @@ struct imsm_disk {

 #define	IMSM_DISK_FILLERS	3

 	__u32 filler[IMSM_DISK_FILLERS]; /* 0xF5 - 0x107 MPB_DISK_FILLERS for future expansion */

 };

+ASSERT_SIZE(imsm_disk, 48)

 /* map selector for map managment

  */

@@ -146,7 +160,8 @@ struct imsm_map {

 	__u32 disk_ord_tbl[1];	/* disk_ord_tbl[num_members],

 				 * top byte contains some flags

 				 */

-} __attribute__ ((packed));

+};

+ASSERT_SIZE(imsm_map, 52)

 struct imsm_vol {

 	__u32 curr_migr_unit;

@@ -169,7 +184,8 @@ struct imsm_vol {

 	__u32 filler[4];

 	struct imsm_map map[1];

 	/* here comes another one if migr_state */

-} __attribute__ ((packed));

+};

+ASSERT_SIZE(imsm_vol, 84)

 struct imsm_dev {

 	__u8  volume[MAX_RAID_SERIAL_LEN];

@@ -220,7 +236,8 @@ struct imsm_dev {

 #define IMSM_DEV_FILLERS 3

 	__u32 filler[IMSM_DEV_FILLERS];

 	struct imsm_vol vol;

-} __attribute__ ((packed));

+};

+ASSERT_SIZE(imsm_dev, 164)

 struct imsm_super {

 	__u8 sig[MAX_SIGNATURE_LENGTH];	/* 0x00 - 0x1F */

@@ -248,7 +265,8 @@ struct imsm_super {

 	struct imsm_disk disk[1];	/* 0xD8 diskTbl[numDisks] */

 	/* here comes imsm_dev[num_raid_devs] */

 	/* here comes BBM logs */

-} __attribute__ ((packed));

+};

+ASSERT_SIZE(imsm_super, 264)

 #define BBM_LOG_MAX_ENTRIES 254

 #define BBM_LOG_MAX_LBA_ENTRY_VAL 256		/* Represents 256 LBAs */

@@ -269,7 +287,8 @@ struct bbm_log {

 	__u32 signature; /* 0xABADB10C */

 	__u32 entry_count;

 	struct bbm_log_entry marked_block_entries[BBM_LOG_MAX_ENTRIES];

-} __attribute__ ((__packed__));

+};

+ASSERT_SIZE(bbm_log, 2040)

 static char *map_state_str[] = { "normal", "uninitialized", "degraded", "failed" };

@@ -323,7 +342,8 @@ struct migr_record {

 				       * destination - high order 32 bits */

 	__u32 num_migr_units_hi;      /* Total num migration units-of-op

 				       * high order 32 bits */

-} __attribute__ ((__packed__));

+};

+ASSERT_SIZE(migr_record, 64)

 struct md_list {

 	/* usage marker:

-- 

2.7.5