• Arnd Bergmann's avatar
    scsi: lpfc: Fix lpfc_name struct packing · 00c2cae6
    Arnd Bergmann authored
    clang points out that the lpfc_name structure has an 8-byte alignment
    requirement on most architectures, but is embedded in a number of other
    structures that are forced to be only 1-byte aligned:
    
    drivers/scsi/lpfc/lpfc_hw.h:1516:30: error: field pe within 'struct lpfc_fdmi_reg_port_list' is less aligned than 'struct lpfc_fdmi_port_entry' and is usually due to 'struct lpfc_fdmi_reg_port_list' being packed, which can lead to unaligned accesses [-Werror,-Wunaligned-access]
            struct lpfc_fdmi_port_entry pe;
    drivers/scsi/lpfc/lpfc_hw.h:850:19: error: field portName within 'struct _ADISC' is less aligned than 'struct lpfc_name' and is usually due to 'struct _ADISC' being packed, which can lead to unaligned accesses [-Werror,-Wunaligned-access]
    drivers/scsi/lpfc/lpfc_hw.h:851:19: error: field nodeName within 'struct _ADISC' is less aligned than 'struct lpfc_name' and is usually due to 'struct _ADISC' being packed, which can lead to unaligned accesses [-Werror,-Wunaligned-access]
    drivers/scsi/lpfc/lpfc_hw.h:922:19: error: field portName within 'struct _RNID' is less aligned than 'struct lpfc_name' and is usually due to 'struct _RNID' being packed, which can lead to unaligned accesses [-Werror,-Wunaligned-access]
    drivers/scsi/lpfc/lpfc_hw.h:923:19: error: field nodeName within 'struct _RNID' is less aligned than 'struct lpfc_name' and is usually due to 'struct _RNID' being packed, which can lead to unaligned accesses [-Werror,-Wunaligned-access]
    
    From the git history, I can see that all the __packed annotations were done
    specifically to avoid introducing implicit padding around the lpfc_name
    instances, though this was probably the wrong approach.
    
    To improve this, only annotate the one uint64_t field inside of lpfc_name
    as packed, with an explicit 4-byte alignment, as is the default already on
    the 32-bit x86 ABI but not on most others. With this, the other __packed
    annotations can be removed again, as this avoids the incorrect padding.
    
    Two other structures change their layout as a result of this change:
    
     - struct _LOGO never gained a __packed annotation even though it has the
       same alignment problem as the others but is not used anywhere in the
       driver today.
    
     - struct serv_param similarly has this issue, and it is used, my guess is
       that this is only an internal structure rather than part of a binary
       interface, so the padding has no negative effect here.
    Signed-off-by: default avatarArnd Bergmann <arnd@arndb.de>
    Link: https://lore.kernel.org/r/20230616090705.2623408-1-arnd@kernel.orgReviewed-by: default avatarJustin Tee <justin.tee@broadcom.com>
    Signed-off-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
    00c2cae6
lpfc_hw.h 130 KB