On 26/04/18 22:21, Marek Vasut wrote:
On 04/26/2018 10:47 PM, Bryan O'Donoghue wrote:
Compiling the f_mass_storage driver for an x86 target results in a
compilation error as set_bit and clear_bit are provided by bitops.h

The local version of set_bit and clear_bit are doing some IP-block specific
bit-twiddling so we don't actually want to accidentally pick up the
bitops.h version of set_bit and clear bit.

This patch renames to _set_bit() and _clear_bit() respectively to avoid the
namespace collision.

Signed-off-by: Bryan O'Donoghue <pure.lo...@nexus-software.ie>
Cc: Lukasz Majewski <lu...@denx.de>
Cc: Marek Vasut <ma...@denx.de>
---
  drivers/usb/gadget/f_mass_storage.c | 8 ++++----
  1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/usb/gadget/f_mass_storage.c 
b/drivers/usb/gadget/f_mass_storage.c
index 1ecb92ac6b..524c43419f 100644
--- a/drivers/usb/gadget/f_mass_storage.c
+++ b/drivers/usb/gadget/f_mass_storage.c
@@ -283,7 +283,7 @@ static const char fsg_string_interface[] = "Mass Storage";
  struct kref {int x; };
  struct completion {int x; };
-inline void set_bit(int nr, volatile void *addr)
+inline void _set_bit(int nr, volatile void *addr)

Do not name functions with _ prefix. Also, I think the suggestion from
Lukasz was better.


Funny - I had assumed we were seting the bit like this for a good reason but...

This code seems to be something that just crept in along the way

inline void set_bit(int nr, volatile void *addr)
{
        int     mask;
        unsigned int *a = (unsigned int *) addr;

        a += nr >> 5;
        mask = 1 << (nr & 0x1f);
        *a |= mask;
}

but on Linux the upstream driver actually does arch-specific set_bit/clear_bit

Looking at it a bit more.. I'm not quite sure how/why we are setting the bit like that

git blame drivers/usb/gadget/f_mass_storage.c

b4d36f6809f (Piotr Wilczek 2013-03-05 12:10:16 +0100 286) inline void set_bit(int nr, volatile void *addr)

The f_mass_storage.c source file from v2.6.36 Linux kernel.

    commit 8876f5e7d3b2a320777dd4f6f5301d474c97a06c
    Author: Michal Nazarewicz <m.nazarew...@samsung.com>
    Date:   Mon Jun 21 13:57:09 2010 +0200


linux$ git checkout 8876f5e7d3b2a320777dd4f6f5301d474c97a06c -- drivers/usb/gadget/f_mass_storage.c

Doesn't have a local copy of set_bit/clear_bit at all, which is confusing - I guess bitops.h in 2013 didn't have set_bit/clear_bit..

But yeah - I guess we really should be using arch-specific get_bit/set_bit after all...

---
bod

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