Re: [Crash-utility] [PATCH v2 1/1] tools: list: create O option for specifying head node offset

Hi Firo, thanks for updating the patch. -----Original Message----- I would like to describe it a bit more and generally here, something like: --- Only used in conjunction with -h, specify the offset of a head node list_head that is embedded within a data structure that is different than the offset of list_head within the other structures in the linked list. --- This might be poor, please help to edit.. That alias is good but it would be better to put an actual output and describe the option more to understand cases that can be used. How about this? --- To display a list that is embedded within a data structure that is different than the offset of list_head within the other structures in the linked list, e.g. dentry.d_subdirs and dentry.d_child, the -O option can be used: %s> list -o dentry.d_child -s dentry.d_name.name -O dentry.d_subdirs -h ffff9c585b81a180 ffff9c585b9cb140 d_name.name = 0xffff9c585b9cb178 "ccc.txt" ffff9c585b9cb980 d_name.name = 0xffff9c585b9cb9b8 "bbb.txt" ffff9c585b9cb740 d_name.name = 0xffff9c585b9cb778 "aaa.txt" The dentry.d_subdirs example above is equal to the following sequence: %s> struct -o dentry.d_subdirs ffff9c585b81a180 struct dentry { [ffff9c585b81a220] struct list_head d_subdirs; } %s> list -o dentry.d_child -s dentry.d_name.name -H ffff9c585b81a220 --- (just fyi, if you want to list directory entries and inodes, the cacheutils extension module may help you: https://github.com/k-hagio/crash-cacheutils) As wrote above, I understand that the following sequence crash> struct -o dentry.d_subdirs ffff9c585b81a180 crash> list -o dentry.d_child -s dentry.d_name.name -H ffff9c585b81a220 is equal to crash> list -o dentry.d_child -s dentry.d_name.name -O dentry.d_subdirs -h ffff9c585b81a180 with the patch. But if the dentry.d_subdirs list is empty, the two results are not equal: crash> list -o dentry.d_child -s dentry.d_name.name -H ffff9c594fb57de0 (empty) crash> list -o dentry.d_child -s dentry.d_name.name -O dentry.d_subdirs -h ffff9c594fb57d40 ffff9c594fb57d50 d_name.name = 0x2e63007974706d65 <Address 0x2e63007974706d65 out of bounds> So, this is also needed? --- a/tools.c +++ b/tools.c @@ -3624,6 +3624,10 @@ next_arg: ld->end = ld->start + head_member_offset; readmem(ld->start + head_member_offset, KVADDR, &ld->start, sizeof(void *), "LIST_HEAD contents", FAULT_ON_ERROR); + if (ld->start == ld->end) { + fprintf(fp, "(empty)\n"); + return; + } } else ld->start += ld->list_head_offset; } Thanks, Kazu