Re: resolution of minor issues

Jeff,

If you have a patch against 2.18.1 for the pipe problem, I will apply it.
Again, perhaps a strtst test case could be added as well.

--brian

On Fri, 29 Oct 2004, Jeff Goldszer wrote:

> 
>    Gentlemen,
> 
>    Below  are  resolutions  to  some  of the issues I reported in earlier
>    emails.  I have emailed a patch to Dave Grothe which addresses items 2
>    and 3. Item 1 is a false alarm.
> 
>    1)       lis_freezestr  and  lis_freezestr do indeed accept any queues
>    other  the  stream  head  pair.  I  misread the code. All queue's have
>    pointers to the stream head (q_str).
> 
>    2)       The  changed  I  made  two  years  ago is still maintained in
>    LiS-2.18  . The problem is a there are places in the code that freemsg
>    on  an  M_PASSFP  message.   The file descriptor in a M_PASSFP message
>    should  be  closed  before  as well as freeing the mblk. The following
>    test  program  can  fail if file descriptor is located on a[0] streams
>    read  put function queue (sd_rput_hd) when a[0] is closed. The failure
>    is  that the file descriptor b[0] will not be freed and LiS can not be
>    unloaded.
> 
>    #include <unistd.h>
> 
>    #include <stropts.h>
> 
>    main()
> 
>    {
> 
>        int a[2];
> 
>        int b[2];
> 
>        pipe(a);
> 
>        pipe(b);
> 
>        ioctl(a[0], I_SENDFD, b[0]);
> 
>        close(b[0]);
> 
>        close(a[1]);
> 
>    }
> 
>    3)       There  is  a  synchronization problem between pipes. One such
>    issue  resulted  in an Oops. The problem is pipe disassemble queues in
>    both  directions.  There  is  an  unprotected critical area. I.e., one
>    process is calling putmsg on one side of a pipe, while another process
>    is closing the other side of the pipe. One process is closing one side
>    of  the  pipe  while  another process is closing the other side of the
>    pipe.
> 
> 
>    Below is the an oops cause by issue 3.
> 
>    Agent:  TERMINATED
> 
>    /u<4s>r//usrsrc//sLircS-/L2.i1S-7/2.h1e7a/d/headed/h.cea       #d.4c17
>    #0:4 1Q7oue:
> 
>    uqe  uemauegi  mc  engiumc benrum biser  0xis93 03x9903d3d90,0 sddh,ou
>    sldho bule
> 
>    d0 bx9e 330x990033dc90
> 
>    dc                                   0
> 
>    Unable  to  handle  kernel NULL pointer dereference at virtual address
>    00000090
> 
>     printing eip:
> 
>    f8a0d9e9
> 
>    *pde  =  00000000
> 
>    Oops:  0002
> 
>    pl2303    usbserial    localdrv   snamux   lu62mux   sessmux   sdlcmux
>    streams-adpa  streams-cxio
> 
>    streams-copier   placxp   slmdrv   streams   bcm5700  st loop  keybdev
>    mousedev  hid  i
> 
>    CPU:           2
> 
>    EIP:             00b0:[<f8a0d9e9>]    Tainted:  PF
> 
>    EFLAGS:     00010046
> 
>    EIP    is   at    lis_rw_write_lock_irqsave_fcn     [streams]     0x11
>    (2.4.21-15.0.4.EL-1/i686)
> 
>    eax:    00000090       ebx:   00000000       ecx:   00000058      edx:
>    00000090
> 
>    esi:   00000058       edi:   eb81b960        ebp:   e4b29e40      esp:
>    eb429e18
> 
>    do:  0068      es: 0068      ss: 0068
> 
>    Process  stopcdm   ( pid: 21360,  stackpage = e4b29000 )
> 
>    Stack:    f89f7158     00000058     e4b29e40     f8a0ef4d     0000104b
>    eb81b960    f8a0ef4d   0000104a
> 
>                  eb81b960    eb81b960     00000246    00000000   00000000
>    eaad2100    eae45d44  f89f73bc
> 
>                  eaad2100    c312c100     eae45d44    00000000   00000000
>    00000001   eae45d44  f89f427b
> 
> 
>    Call   Trace:   [<f89f7158>]  check_for_wantenable  [streams]  0x94  (
>    0xe4b29e18 )
> 
>    [<f8a0ef4d>]  .rodata.str1.1  [streams]  0x2fd  (0xe4b29e24 )
> 
>    [<f8a0ef4d>]  .rodata.str1.1  [streams]  0x2fd  ( 0xe4b29e30 )
> 
>    [<f89f73bc>]  lis_unfreezestr  [streams]  0x64  ( 0xe4b29e54 )
> 
>    [<f89f427b>]  lis_qdetach  [streams]  0x54b  ( 0xe4b29e74 )
> 
>    [<f8a0ef4d>]  .rodata.str1.1  [streams]  0x2fd  ( 0xe4b29ea4 )
> 
>    [<f89f2e21>]  lis_dismantle  [streams]  0x61  ( 0xe4b29ed0 )
> 
>    [<f89fcfe3>]  close_action  [streams]  0x197  ( 0xe4b29eec )
> 
>    [<f89fd5a0>] lis_doclose  [streams]  0x328  ( 0xe4b29f18 )
> 
>    [<f89fd7a0>]  lis_strclose  [streams]  0x178  ( 0xe4b29f44 )
> 
>    [<c015507b>]  __fput  [kernel]  0xe4  ( 0xe4b29f78 )
> 
>    [<c0153440>]  filp_close  [kernel]  0x92  ( 0xe4b29f94 )
> 
>    [<c01534e2>]  sys_close  [kernel]  0x66  ( 0xe4b29fb0 )
> 
>    Code:    f0    81   28    00    00    00   01   0f   85   a8   06   00
>    00   b8   00   ff   21   e0
> 
>    Kernel panic:   Fatal exception
> 
>    Jeff Goldszer
> 
>    Senior Software Engineer
> 
>    Alebra Technologies
> 
>    9915 66th Avenue
> 
>    Apartment 2C
> 
>    Rego Park, NY 11374
> 
>    Phone: 718-606-8535
> 
>    FAX:  718-606-8536

-- 
Brian F. G. Bidulock    ¦ The reasonable man adapts himself to the ¦
[email protected]    ¦ world; the unreasonable one persists in  ¦
http://www.openss7.org/ ¦ trying  to adapt the  world  to himself. ¦
                        ¦ Therefore  all  progress  depends on the ¦
                        ¦ unreasonable man. -- George Bernard Shaw ¦