Priya Krishnan wrote:
I need help in understanding this alignment error. The error message is
dtrace: error on enabled probe ID 14 (ID 24380:
iscsi:idm:idm_pdu_rx_forward_ffp:nop-receive): invalid alignment
(0xffffff03df31b06c) in action #1 at DIF offset 32
This is a new probe that has two arguments - conninfo_t and iscsiinfo_t
In my D script, I print out just the datalen field from argument 1.
iscsi:::
{
printf("datalen[%d],", args[1]->ii_datalen);
}
I use a translator to translate from C struct iscsi_nop_out_hdr_t to D
struct iscsiinfo_t
The D struct iscsiinfo_t is defined as
typedef struct iscsiinfo {
string ii_target; /* target iqn */
string ii_initiator; /* initiator iqn */
string ii_isid; /* initiator session identifier */
string ii_tsih; /* target session identifying handle */
string ii_transport; /* transport type ("iser-ib",
"sockets") */
uint64_t ii_lun; /* target logical unit number */
uint32_t ii_itt; /* initiator task tag */
uint32_t ii_ttt; /* target transfer tag */
uint32_t ii_cmdsn; /* command sequence number */
uint32_t ii_statsn; /* status sequence number */
uint32_t ii_datasn; /* data sequence number */
uint32_t ii_datalen; /* length of data payload */
uint32_t ii_flags; /* probe-specific flags */
} iscsiinfo_t;
The native structure is defined as
/* NOP-Out Message */
typedef struct _iscsi_nop_out_hdr {
uint8_t opcode;
uint8_t flags;
uint16_t rsvd2;
uint8_t rsvd3;
uint8_t dlength[3];
uint8_t lun[8];
uint32_t itt; /* Initiator Task Tag */
uint32_t ttt; /* Target Transfer Tag */
uint32_t cmdsn;
uint32_t expstatsn;
uint8_t rsvd4[16];
} iscsi_nop_out_hdr_t;
My translator looks like this
#pragma D binding "1.5" translator
translator iscsiinfo_t < iscsi_nop_out_hdr_t *P > {
<snip>
<snip>
ii_datalen = P->dlength[0] << 16 || P->dlength[1] << 8 ||
P->dlength[2];
};
Any hints on how I can debug this problem is appreciated
Hmm... nothing jumps out at me right off -- the address is
4-byte-aligned and you don't access any 8-byte values that I can see.
Unless struct iscsiinfo somehow doesn't get 8-byte-aligned and you
actually croak while initializing ii_lun? What happens if you move
ii_lun to be the first member of the struct? Those strings are just
char[256] (unless you've changed the size limit), and don't impose any
alignment constraints. It shouldn't matter, but who knows... You could
also try not initializing ii_lun at all to see if the error disappears,
though that's obviously not a permanent solution.
BTW, you are using logical '||' instead bitwise '|' to reconstruct
ii_datalen, which is probably not what you want.
Regards,
Ryan
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