File 0052-super-intel-don-t-mark-structs-packed-unnecessarily.patch of Package mdadm.30550
From 761e3bd9f5e3aafa95ad3ae50a637dc67c8774f0 Mon Sep 17 00:00:00 2001
From: NeilBrown <neilb@suse.de>
Date: Thu, 31 Oct 2019 15:15:38 +1100
Subject: [PATCH] super-intel: don't mark structs 'packed' unnecessarily
Git-commit: 761e3bd9f5e3aafa95ad3ae50a637dc67c8774f0
Patch-mainline: mdadm-4.1+
References: jsc#SLE-10078, jsc#SLE-9348
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>
Signed-off-by: Coly Li <colyli@suse.de>
---
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:
--
2.25.0
