Messages in this thread | | | Date | Mon, 13 Mar 2023 12:07:27 -0700 | Subject | Re: [PATCH 32/36] dmaengine: idxd: use const struct bus_type * | From | Fenghua Yu <> |
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Hi, Greg,
On 3/13/23 11:29, Greg Kroah-Hartman wrote: > In the functions unbind_store() and bind_store(), a struct bus_type * > should be a const one, as the driver core bus functions used by this > variable are expecting the pointer to be constant, and these functions > do not modify the pointer at all. > > Cc: Fenghua Yu <fenghua.yu@intel.com> > Cc: Dave Jiang <dave.jiang@intel.com> > Cc: Vinod Koul <vkoul@kernel.org> > Cc: dmaengine@vger.kernel.org > Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> > --- > Note, this is a patch that is a prepatory cleanup as part of a larger > series of patches that is working on resolving some old driver core > design mistakes. It will build and apply cleanly on top of 6.3-rc2 on > its own, but I'd prefer if I could take it through my driver-core tree > so that the driver core changes can be taken through there for 6.4-rc1. > > drivers/dma/idxd/compat.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/dma/idxd/compat.c b/drivers/dma/idxd/compat.c > index 3df21615f888..5fd38d1b9d28 100644 > --- a/drivers/dma/idxd/compat.c > +++ b/drivers/dma/idxd/compat.c > @@ -16,7 +16,7 @@ extern void device_driver_detach(struct device *dev); > > static ssize_t unbind_store(struct device_driver *drv, const char *buf, size_t count) > { > - struct bus_type *bus = drv->bus; > + const struct bus_type *bus = drv->bus; > struct device *dev; > int rc = -ENODEV; > > @@ -32,7 +32,7 @@ static DRIVER_ATTR_IGNORE_LOCKDEP(unbind, 0200, NULL, unbind_store); > > static ssize_t bind_store(struct device_driver *drv, const char *buf, size_t count) > { > - struct bus_type *bus = drv->bus; > + const struct bus_type *bus = drv->bus; > struct device *dev; > struct device_driver *alt_drv = NULL; > int rc = -ENODEV;
After applying this patch, warning is reported:
drivers/dma/idxd/compat.c: In function ‘bind_store’: drivers/dma/idxd/compat.c:47:47: warning: passing argument 2 of ‘driver_find’ discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers] 47 | alt_drv = driver_find("idxd", bus); | ^~~ In file included from ./include/linux/device.h:32, from drivers/dma/idxd/compat.c:6: ./include/linux/device/driver.h:129:59: note: expected ‘struct bus_type *’ but argument is of type ‘const struct bus_type *’ 129 | struct bus_type *bus); | ~~~~~~~~~~~~~~~~~^~~
Should the "bus" parameter in driver_find() definition be changed to const as well to avoid the warning?
Thanks.
-Fenghua
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