Messages in this thread | | | Date | Tue, 12 Jun 2007 09:55:17 -0500 | From | "Nelson Castillo" <> | Subject | Re: [RFC][PATCH 1/1] support for user-space buffers in kfifo |
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On 6/12/07, Stelian Pop <stelian@popies.net> wrote: > Le lundi 11 juin 2007 à 16:26 -0500, Nelson Castillo a écrit : > > Hi. > > > > I just added support for user space buffers in kfifo. I found useful > > __kfifo_get_user to copy data to a user buffer in a read call. I didn't > > like the idea of having an extra buffer. > > > > * Is it ok to add this support? > > I suppose it is, however: > > > + spin_lock_irqsave(fifo->lock, flags); > > + > > + ret = __kfifo_put_user(fifo, buffer, len); > > + > > + spin_unlock_irqrestore(fifo->lock, flags); > [...] > > > +int __kfifo_put_user(struct kfifo *fifo, const unsigned char __user *buffer, > > + unsigned int len) > [...] > > > + if(copy_from_user(fifo->buffer + (fifo->in & (fifo->size - 1)), > > + buffer, l)) > > + return -EFAULT; > [...] > > accessing userspace memory with a spinlock taken (moreover an irqsave() > one) is bad bad bad.
Yes.
Perhaps then only the functions __kfifo_put_user and __kfifo_get_user should be allowed. Those are the ones I'm using now , anyway. I added the others for completeness but adding them is probably a mistake.
Regards, Nelson.-
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