[Crash-utility] [PATCH] add a new command: ipcs

[Dave Anderson]

----- Original Message -----
> Hello Dave,
> 
> I cannot get all kernels at hand. So I have to ask you about the code.
> Please show me.

Why not?  Just download the upstream kernels from here:

  http://www.kernel.org/pub/linux/kernel/v2.6/
 
> >
> > (a) On these kernel versions:
> >
> >      2.6.9-89.ELxenU
> >      2.6.15-1.2054_FC5
> >      2.6.16.33-xen
> >      2.6.18-1.2714.el5xen
> >      2.6.18-36.el5xen
> >      2.6.18-58.el5xen
> >      2.6.18-152.el5xen
> >      2.6.31 uniprocessor kernel
> >
> >      the command fails immediatedly with this error:
> >
> >        ipcs: cannot resolve "hugetlbfs_file_operations"
> >
> >
> > (b) On *all* RHEL5 2.6.18-era kernels, the message queue display
> >      always fails like this:
> >
> >      ------ Message Queues --------
> >      KEY        MSQID      UID        PERMS      USED-BYTES
> >        MESSAGES
> >      ipcs: invalid structure member offset: kern_ipc_perm_id
> >            FILE: ipcs.c  LINE: 899  FUNCTION: get_msg_info()
> 
> I want to see the struct msg_queue and struct struct kern_ipc_perm.

Here is the output from a RHEL5 kernel:
 
 crash> msg_queue
 struct msg_queue {
     struct kern_ipc_perm q_perm;
     int q_id;
     time_t q_stime;
     time_t q_rtime;
     time_t q_ctime;
     long unsigned int q_cbytes;
     long unsigned int q_qnum;
     long unsigned int q_qbytes;
     pid_t q_lspid;
     pid_t q_lrpid;
     struct list_head q_messages;
     struct list_head q_receivers;
     struct list_head q_senders;
 }
 SIZE: 160
 crash> kern_ipc_perm
 struct kern_ipc_perm {
     spinlock_t lock;
     int deleted;
     key_t key;
     uid_t uid;
     gid_t gid;
     uid_t cuid;
     gid_t cgid;
     mode_t mode;
     long unsigned int seq;
     void *security;
 }
 SIZE: 48
 crash>

which is the same as the upstream 2.6.18 kernel.

> >
> > (c) On this 2.6.36-0.16.rc3.git0.fc15 Fedora kernel, it shows:
> >
> >      ------ Shared Memory Segments ------
> >      KEY        SHMID      UID        PERMS      BYTES      NATTCH
> >          STATUS
> >      ipcs: invalid kernel virtual address: 10  type: "nsproxy.ipc_ns"
> 
> what is struct nsproxy? Or is there any symbol referring to ipc_ns?

 crash> nsproxy
 struct nsproxy {
     atomic_t count;
     struct uts_namespace *uts_ns;
     struct ipc_namespace *ipc_ns;
     struct mnt_namespace *mnt_ns;
     struct pid_namespace *pid_ns;
     struct net *net_ns;
 }
 SIZE: 48
 crash> 

It's the same as upstream 2.6.36, but it's not the offset that's invalid, 
it's the NULL "nsproxy" address.
 
> 
> >
> >
> > (d) On *all* RHEL4 2.6.9-era and SLES9 2.6.5-era kernels, the
> > command fail like this:
> >
> >      ------ Shared Memory Segments ------
> >      KEY        SHMID      UID        PERMS      BYTES      NATTCH
> >          STATUS
> >      ipcs: invalid structure member offset: ipc_id_ary_p
> >            FILE: ipcs.c  LINE: 540  FUNCTION: ipc_search_array()
> >
> >      or this:
> >
> >      ------ Shared Memory Segments ------
> >      KEY        SHMID      UID        PERMS      BYTES      NATTCH
> >          STATUS
> >      (none allocated)------ Semaphore Arrays --------
> >      KEY        SEMID      UID        PERMS      NSEMS
> >      ipcs: invalid structure member offset: ipc_id_ary_p
> >            FILE: ipcs.c  LINE: 540  FUNCTION: ipc_search_array()
> >
> 
> what is struct ipc_id? And what is entries in struct ipc_id or something
> similar to it?

This is from a RHEL4 kernel -- and the upstream 2.6.9 kernel is the same:

 crash> ipc_id
 struct ipc_id {
     struct kern_ipc_perm *p;
 }
 SIZE: 8
 crash> kern_ipc_perm
 struct kern_ipc_perm {
     spinlock_t lock;
     int deleted;
     key_t key;
     uid_t uid;
     gid_t gid;
     uid_t cuid;
     gid_t cgid;
     mode_t mode;
     long unsigned int seq;
     void *security;
 }
 SIZE: 56
 crash> 

Dave