On Mon, Aug 21, 2017 at 04:18:44PM +0000, Bart Van Assche wrote: > On Mon, 2017-08-21 at 15:12 +0200, Lukas Wunner wrote: > > Cc: Bart Van Assche <bart.vanass...@wdc.com> > > Cc: Alasdair Kergon <a...@redhat.com> > > Cc: Mike Snitzer <snit...@redhat.com> > > Signed-off-by: Lukas Wunner <lu...@wunner.de> > > This Cc-list is incomplete. Previous <linux/bitops.h> patches went in > through Andrew Morton's tree so I think an ack from Andrew Morton is > needed before this patch can be sent to Linus Torvalds. Please also > Cc other frequent contributors to this header file, e.g. Ingo Molnar > and Peter Zijlstra. Please also consider to Cc the LKML for this patch > or even for the entire series.
Fair enough, adding more folks to cc. Does anyone have objections or comments to the below patch and to merging it through linux-gpio? It's part of this series: https://www.spinics.net/lists/linux-gpio/msg25067.html Looking at the mnemonics of x86 and arm I couldn't find one which would avoid the jump and be faster/shorter than the inline functions below, so putting this in include/linux/bitops.h (rather than arch/*/include/asm/) seemed appropriate. Can anyone imagine doing the same quicker with inline assembly? > > +static __always_inline void assign_bit(bool value, long nr, > > + volatile unsigned long *addr) > > Why has __always_inline been specified? What makes you think that you know > better than the compiler whether or not these functions should be inlined? I carried this over from existing functions, see e.g. commit 1a1d48a4a8fd ("linux/bitmap: Force inlining of bitmap weight functions"). Thanks, Lukas -- >8 -- Subject: [PATCH 1/4] bitops: Introduce assign_bit() A common idiom is to assign a value to a bit with: if (value) set_bit(nr, addr); else clear_bit(nr, addr); Likewise common is the one-line expression variant: value ? set_bit(nr, addr) : clear_bit(nr, addr); Commit 9a8ac3ae682e ("dm mpath: cleanup QUEUE_IF_NO_PATH bit manipulation by introducing assign_bit()") introduced assign_bit() to the md subsystem for brevity. Make it available to others, in particular gpiolib and the upcoming driver for Maxim MAX3191x industrial serializer chips. Cc: Bart Van Assche <bart.vanass...@wdc.com> Cc: Alasdair Kergon <a...@redhat.com> Cc: Mike Snitzer <snit...@redhat.com> Signed-off-by: Lukas Wunner <lu...@wunner.de> --- drivers/md/dm-mpath.c | 8 -------- include/linux/bitops.h | 24 ++++++++++++++++++++++++ 2 files changed, 24 insertions(+), 8 deletions(-) diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c index 0e8ab5bb3575..c79c113b7e7d 100644 --- a/drivers/md/dm-mpath.c +++ b/drivers/md/dm-mpath.c @@ -638,14 +638,6 @@ static void process_queued_bios(struct work_struct *work) blk_finish_plug(&plug); } -static void assign_bit(bool value, long nr, unsigned long *addr) -{ - if (value) - set_bit(nr, addr); - else - clear_bit(nr, addr); -} - /* * If we run out of usable paths, should we queue I/O or error it? */ diff --git a/include/linux/bitops.h b/include/linux/bitops.h index a83c822c35c2..097af36887c0 100644 --- a/include/linux/bitops.h +++ b/include/linux/bitops.h @@ -226,6 +226,30 @@ static inline unsigned long __ffs64(u64 word) return __ffs((unsigned long)word); } +/** + * assign_bit - Assign value to a bit in memory + * @value: the value to assign + * @nr: the bit to set + * @addr: the address to start counting from + */ +static __always_inline void assign_bit(bool value, long nr, + volatile unsigned long *addr) +{ + if (value) + set_bit(nr, addr); + else + clear_bit(nr, addr); +} + +static __always_inline void __assign_bit(bool value, long nr, + volatile unsigned long *addr) +{ + if (value) + __set_bit(nr, addr); + else + __clear_bit(nr, addr); +} + #ifdef __KERNEL__ #ifndef set_mask_bits -- 2.11.0
