On Mon, Jan 07, 2019 at 03:44:38PM -0800, David Tolnay wrote: > From: David Tolnay <dtolnay@xxxxxxxxx> > Date: Mon, 7 Jan 2019 14:36:11 -0800 > Subject: [PATCH] virtio-rng: Avoid repeated init of completion > > The virtio-rng driver uses a completion called have_data to wait for a > virtio read to be fulfilled by the hypervisor. The completion is reset > before placing a buffer on the virtio queue and completed by the virtio > callback once data has been written into the buffer. > > Prior to this commit, the driver called init_completion on this > completion both during probe as well as when registering virtio buffers > as part of a hwrng read operation. The second of these init_completion > calls should instead be reinit_completion because the have_data > completion has already been inited by probe. As described in > Documentation/scheduler/completion.txt, "Calling init_completion() twice > on the same completion object is most likely a bug". > > This bug was present in the initial implementation of virtio-rng in > f7f510ec1957 ("virtio: An entropy device, as suggested by hpa"). Back > then the have_data completion was a single static completion rather than > a member of one of potentially multiple virtrng_info structs as > implemented later by 08e53fbdb85c ("virtio-rng: support multiple > virtio-rng devices"). The original driver incorrectly used > init_completion rather than INIT_COMPLETION to reset have_data during > read. > > Tested by running `head -c48 /dev/random | hexdump` within crosvm, the > Chrome OS virtual machine monitor, and confirming that the virtio-rng > driver successfully produces random bytes from the host. > > Signed-off-by: David Tolnay <dtolnay@xxxxxxxxx> > Tested-by: David Tolnay <dtolnay@xxxxxxxxx> > --- > drivers/char/hw_random/virtio-rng.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) Thanks, but your patch doesn't apply because it is white-space damaged. Please resubmit. -- Email: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx> Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt