Messages in this thread | | | Date | Mon, 21 Sep 2009 15:38:57 +0100 | From | Al Viro <> | Subject | Re: [PATCH 2/2] vfs: fix d_path() for unreachable paths |
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On Mon, Sep 21, 2009 at 10:10:17AM -0400, Mike Frysinger wrote:
> it works without having to copy & paste the same exact structures over > and over. a suggestion as how to do it cleanly without bloating the > code is certainly welcome. it doesnt really matter that it's on the > stack as the usage is small and d_path() is given the size of the > buffer, so it isnt going to overflow.
Umm... Surely, you can put a CPU number + one bit into PDE->data? As in proc_create_data("icplb", ....., (void *)(cpu * 2)) proc_create_data("dcplb", ....., (void *)(cpu * 2 + 1)) and struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode); unsigned long n = (unsigned long) pde->data; ... cpu = n / 2; is_D = n & 1;
> > ??For another... locking in that loop > > over processes and VMAs of each looks very suspicios, while we are at it. > > we've reviewed it several times and exercised it in multiple ways. so > unless you have a real idea of something being wrong, the code has > been vetted heavily.
write_lock_irq tasklist_lock loop over processes get_task_mm [now VM is pinned down, but not locked] walk the VMA list without any locking
Something on another CPU (you have SMP systems, judging by the previously discussed code, right?) does munmap().
Boom.
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