Re: [PATCH] WorkStruct: Implement generic UP cmpxchg() where an arch doesn't support it

Russell King <[email protected]> wrote:

> Yes you can.  Well, you can on ARM at least.  Between the load exclusive
> you can do anything you like until you hit the store exclusive.

How come atomic_set() on arm6 is implemented as:

	static inline void atomic_set(atomic_t *v, int i)
	{
		unsigned long tmp;

		__asm__ __volatile__("@ atomic_set\n"
	"1:	ldrex	%0, [%1]\n"
	"	strex	%0, %2, [%1]\n"
	"	teq	%0, #0\n"
	"	bne	1b"
		: "=&r" (tmp)
		: "r" (&v->counter), "r" (i)
		: "cc");
	}

Why LDREX/STREX and not direct assignment?

David
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

---

• References:
  • Re: [PATCH] WorkStruct: Implement generic UP cmpxchg() where an arch doesn't support it
    • From: Russell King <[email protected]>
  • Re: [PATCH] WorkStruct: Implement generic UP cmpxchg() where an arch doesn't support it
    • From: Christoph Lameter <[email protected]>
  • Re: [PATCH] WorkStruct: Implement generic UP cmpxchg() where an arch doesn't support it
    • From: Russell King <[email protected]>
  • Re: [PATCH] WorkStruct: Implement generic UP cmpxchg() where an arch doesn't support it
    • From: Christoph Lameter <[email protected]>
  • Re: [PATCH] WorkStruct: Implement generic UP cmpxchg() where an arch doesn't support it
    • From: Russell King <[email protected]>
  • Re: [PATCH] WorkStruct: Implement generic UP cmpxchg() where an arch doesn't support it
    • From: Nick Piggin <[email protected]>
  • Re: [PATCH] WorkStruct: Implement generic UP cmpxchg() where an arch doesn't support it
    • From: Russell King <[email protected]>
  • Re: [PATCH] WorkStruct: Implement generic UP cmpxchg() where an arch doesn't support it
    • From: Nick Piggin <[email protected]>
  • Re: [PATCH] WorkStruct: Implement generic UP cmpxchg() where an arch doesn't support it
    • From: Russell King <[email protected]>
  • Re: [PATCH] WorkStruct: Implement generic UP cmpxchg() where an arch doesn't support it
    • From: David Howells <[email protected]>
  • Re: [PATCH] WorkStruct: Implement generic UP cmpxchg() where an arch doesn't support it
    • From: Linus Torvalds <[email protected]>

• Prev by Date: Segmentation fault on modprobe depca
• Next by Date: [RFC 2.6.19 1/1] fbdev,mm: hecuba/E-Ink fbdev driver v2
• Previous by thread: Re: [PATCH] WorkStruct: Implement generic UP cmpxchg() where an arch doesn't support it
• Next by thread: Re: [PATCH] WorkStruct: Implement generic UP cmpxchg() where an arch doesn't support it
• Index(es):
  • Date
  • Thread

[Index of Archives]     [Kernel Newbies]     [Netfilter]     [Bugtraq]     [Photo]     [Stuff]     [Gimp]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Video 4 Linux]     [Linux for the blind]     [Linux Resources]