Messages in this thread | | | From | David Brownell <> | Subject | Re: [linux-usb-devel] device struct bloat | Date | Mon, 5 Nov 2007 17:38:34 -0800 |
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On Monday 05 November 2007, Greg KH wrote: > --- linux-2.6-2.orig/drivers/spi/spi.c > +++ linux-2.6-2/drivers/spi/spi.c
It'd be quicker to end up in the right hands if you had split this big and random patch according to subsystem...
There's already a patch in the MM queue that removes the SPI-private semaphore. Except that it's missing the bug noted below.
The class semaphore removal would be a different issue.
> @@ -613,7 +613,7 @@ int spi_write_then_read(struct spi_devic > } > > /* ... unless someone else is using the pre-allocated buffer */ > - if (down_trylock(&lock)) { > + if (mutex_trylock(&lock)) {
According to its kerneldoc, mutex_trylock() follows the spinlock model not the semaphore model. So the sense of this test is incorrect ... as will be any similar changes in other parts of this patch:
* NOTE: this function follows the spin_trylock() convention, so * it is negated to the down_trylock() return values! Be careful * about this when converting semaphore users to mutexes.
So the patch in the MM queue says "if (!mutex_trylock(...)) {
> local_buf = kmalloc(SPI_BUFSIZ, GFP_KERNEL); > if (!local_buf) > return -ENOMEM;
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