On Sat, 2010-12-11 at 21:35 -0600, Larry Finger wrote:
> @@ -1013,6 +1013,7 @@ void ssb_pci_exit(struct ssb_bus *bus)
> if (bus->bustype != SSB_BUSTYPE_PCI)
> return;
>
> + kfree(bus->sprom_data);
> pdev = bus->host_pci;
> device_remove_file(&pdev->dev, &dev_attr_ssb_sprom);
> }
Need to put kfree after removing the sprom file. Otherwise there's
a race condition with userspace.
> Index: wireless-testing/drivers/ssb/sprom.c
> ===================================================================
> --- wireless-testing.orig/drivers/ssb/sprom.c
> +++ wireless-testing/drivers/ssb/sprom.c
> @@ -72,24 +72,29 @@ ssize_t ssb_attr_sprom_show(struct ssb_b
> ssize_t count = 0;
> size_t sprom_size_words = bus->sprom_size;
>
> - sprom = kcalloc(sprom_size_words, sizeof(u16), GFP_KERNEL);
> - if (!sprom)
> - goto out;
> -
> - /* Use interruptible locking, as the SPROM write might
> - * be holding the lock for several seconds. So allow userspace
> - * to cancel operation. */
> - err = -ERESTARTSYS;
> - if (mutex_lock_interruptible(&bus->sprom_mutex))
> - goto out_kfree;
> - err = sprom_read(bus, sprom);
> - mutex_unlock(&bus->sprom_mutex);
> -
> + if (bus->sprom_data) {
> + sprom = bus->sprom_data;
> + err = 0;
> + } else {
This branch is dead now, or do I miss something?
> + sprom = kcalloc(sprom_size_words, sizeof(u16), GFP_KERNEL);
> + if (!sprom)
> + goto out;
> +
> + /* Use interruptible locking, as the SPROM write might
> + * be holding the lock for several seconds. So allow userspace
> + * to cancel operation. */
> + err = -ERESTARTSYS;
> + if (mutex_lock_interruptible(&bus->sprom_mutex))
> + goto out_kfree;
> + err = sprom_read(bus, sprom);
> + mutex_unlock(&bus->sprom_mutex);
> + }
> if (!err)
> count = sprom2hex(sprom, buf, PAGE_SIZE, sprom_size_words);
>
> out_kfree:
> - kfree(sprom);
> + if (!bus->sprom_data)
> + kfree(sprom);
> out:
> return err ? err : count;
> }
I agree that caching the SPROM probably is easier than reading it from
the wireless core at sysfs read time. There are a few concurrency issues
that are hard to solve with the current ssb-pci MMIO access code.
Most notably is that the SPROM read would race with wireless interrupts.
--
Greetings Michael.
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