[Valgrind-users] not understanding some valgrind errors against afs...

[Nathan N. <nn...@um...>]

First off, openafs is doing some user-space threading using setjmp/etc.
There seems to be a mention in the valgrind docs about maybe having
trouble with this, if this is the problem, is there any workaround?

First, what is the problem here:

==26290== Invalid write of size 4
==26290==    at 0x8097889: rxi_AllocPacketNoLock
(/umr/s/openafs/openafs/src/rx/rx_packet.c:637)
==26290==    by 0x8097927: rxi_AllocSendPacket
(/umr/s/openafs/openafs/src/rx/rx_packet.c:674)
==26290==    by 0x809B463: rxi_WriteProc
(/umr/s/openafs/openafs/src/rx/rx_rdwr.c:731)
==26290==    by 0x809B963: rx_WriteProc32
(/umr/s/openafs/openafs/src/rx/rx_rdwr.c:909)
==26290==    Address 0x4106C444 is 16552 bytes inside a block of size
80752 alloc'd
==26290==    at 0x40166741: malloc (vg_clientfuncs.c:103)
==26290==    by 0x80972F2: rxi_MorePackets
(/umr/s/openafs/openafs/src/rx/rx_packet.c:366)
==26290==    by 0x808BA70: rx_Init
(/umr/s/openafs/openafs/src/rx/rx.c:458)
==26290==    by 0x806A7A1: vsu_ClientInit
(/umr/s/openafs/openafs/src/volser/vsutils.c:425)


Why is the read invalid if it's a 4 byte read 16552 bytes inside a block
of size 80752? 

Second, how can this code:


afs_int32 savecontext(ep, savearea, sp)
char    (*ep)();
struct lwp_context *savearea;
char*   sp;
{
        int code;

        PRE_Block = 1;
        EP = ep;

        code =  setjmp(savearea->setjmp_buffer);
        jmpBuffer = (jmp_buf_type *)savearea->setjmp_buffer;
        savearea->topstack = (char*)jmpBuffer[LWP_SP];

#if     defined(DEBUG)
        {
            int i, *ptr = (int*)savearea->setjmp_buffer;
            printf("savecontext\n");
            for ( i=0; i < 5; i++)
                printf("(%d) 0x%x   ",i, ptr[i]);
            printf("\n");
            for ( i=5; i < 10; i++)
                printf("(%d) 0x%x   ",i, ptr[i]);
            printf("\n");
        }
#endif
        switch ( code )
        {
                case 0: if ( !sp )
                        (*EP)();
                        else


generate a unitialized error on the "switch ( code )" line? That doesn't
seem to be possible unless the setjmp is returning an unitialized value
as it's result.

-- Nathan

------------------------------------------------------------
Nathan Neulinger                       EMail:  nn...@um...
University of Missouri - Rolla         Phone: (573) 341-4841
Computing Services                       Fax: (573) 341-4216