vn_fullpath: 0xc85e24a0 is not locked but should be
Don Lewis
truckman at FreeBSD.org
Fri Dec 12 10:35:48 PST 2003
On 12 Dec, Jun Kuriyama wrote:
> At Thu, 11 Dec 2003 23:14:50 -0500 (EST),
> Robert Watson wrote:
>> Ah, you're still runing with the VFS lock debugging :-). Indeed, it looks
>> like a vn_lock() and unlock of p->p_textvp is missing in
>> procfs_doprocfile(), even though that likely would violate the VFS lock
>> order. The attached (untested) patch might well fix it, but might not be
>> right -- I'm not sure that curthread holds a valid reference to
>> p->p_textvp that can't evaporate during these operations. I'm not sure
>> the proc reference stuff protects us properly here, but John would know
>> (CC'd).
>>
>> Index: procfs.c
>> ===================================================================
>> RCS file: /home/ncvs/src/sys/fs/procfs/procfs.c,v
>> retrieving revision 1.9
>> diff -u -r1.9 procfs.c
>> --- procfs.c 17 Apr 2003 22:12:12 -0000 1.9
>> +++ procfs.c 12 Dec 2003 04:13:10 -0000
>> @@ -70,7 +70,9 @@
>> char *fullpath = "unknown";
>> char *freepath = NULL;
>>
>> + vn_lock(p->p_textvp, LK_EXCLUSIVE | LK_RETRY, td);
>> vn_fullpath(td, p->p_textvp, &fullpath, &freepath);
>> + VOP_UNLOCK(p->p_textvp, 0, td);
>> sbuf_printf(sb, "%s", fullpath);
>> if (freepath)
>> free(freepath, M_TEMP);
>
> Okay, I'll wait without DEBUG_VFS_LOCKS until fix is committed.
DEBUG_VFS_LOCKS is quite usable as long as you don't run find, tar, etc.
that traverses procfs.
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