Re: Problem with using spinlocks when kernel is compiled withoutsmp-support

[linux-os (Dick Johnson)]

On Thu, 8 Dec 2005, Dirk Henning Gerdes wrote:

> Hello Andrew!
>
> I have the following problem on 2.6.15-rc5-mm1
>
> When compiling a module using spinlocks I get the following
> error-message, when SMP is disabled in my Kernel-config:
>
>
>
>
> In file included from /home/dirk/Masterarbeit/mynoop/test/mynoop.c:7:
> include/asm/spinlock.h:21:1: warning: "__raw_spin_is_locked" redefined
> In file included from include/linux/spinlock.h:90,
>                 from include/linux/kobject.h:23,
>                 from include/linux/device.h:16,
>                 from include/linux/genhd.h:15,
>                 from include/linux/blkdev.h:6,
>                 from /home/dirk/Masterarbeit/mynoop/test/mynoop.c:1:
> include/linux/spinlock_up.h:61:1: warning: this is the location of the
> previous definition
> In file included from /home/dirk/Masterarbeit/mynoop/test/mynoop.c:7:
> include/asm/spinlock.h:51: error: syntax error before 'do'
> include/asm/spinlock.h: In function '__raw_spin_lock_flags':
> include/asm/spinlock.h:62: error: 'struct <anonymous>' has no member
> named 'slock'
> include/asm/spinlock.h:60: error: invalid lvalue in asm output 0
> include/asm/spinlock.h: At top level:
> include/asm/spinlock.h:65: error: syntax error before '{' token
> include/asm/spinlock.h:89: error: syntax error before 'do'
> In file included from /home/dirk/Masterarbeit/mynoop/test/mynoop.c:7:
> include/asm/spinlock.h:114:1: warning: "__raw_spin_unlock_wait"
> redefined
> In file included from include/linux/spinlock.h:90,
>                 from include/linux/kobject.h:23,
>                 from include/linux/device.h:16,
>                 from include/linux/genhd.h:15,
>                 from include/linux/blkdev.h:6,
>                 from /home/dirk/Masterarbeit/mynoop/test/mynoop.c:1:
> include/linux/spinlock_up.h:71:1: warning: this is the location of the
> previous definition
> In file included from /home/dirk/Masterarbeit/mynoop/test/mynoop.c:7:
> include/asm/spinlock.h:142:1: warning: "__raw_read_can_lock" redefined
> In file included from include/linux/spinlock.h:90,
>                 from include/linux/kobject.h:23,
>                 from include/linux/device.h:16,
>                 from include/linux/genhd.h:15,
>                 from include/linux/blkdev.h:6,
>                 from /home/dirk/Masterarbeit/mynoop/test/mynoop.c:1:
> include/linux/spinlock_up.h:68:1: warning: this is the location of the
> previous definition
> In file included from /home/dirk/Masterarbeit/mynoop/test/mynoop.c:7:
> include/asm/spinlock.h:148:1: warning: "__raw_write_can_lock" redefined
> In file included from include/linux/spinlock.h:90,
>                 from include/linux/kobject.h:23,
>                 from include/linux/device.h:16,
>                 from include/linux/genhd.h:15,
>                 from include/linux/blkdev.h:6,
>                 from /home/dirk/Masterarbeit/mynoop/test/mynoop.c:1:
> include/linux/spinlock_up.h:69:1: warning: this is the location of the
> previous definition
> include/asm/spinlock.h: In function '__raw_read_unlock':
> include/asm/spinlock.h:181: error: 'struct <anonymous>' has no member
> named 'lock'
> include/asm/spinlock.h:181: error: invalid lvalue in asm output 0
> include/asm/spinlock.h: In function '__raw_write_unlock':
> include/asm/spinlock.h:187: error: 'struct <anonymous>' has no member
> named 'lock'
> include/asm/spinlock.h:186: error: invalid lvalue in asm output 0
>
>
>
> shouldn't it be possible to use spinlocks in my code even if I don't
> support SMP for compatiblity ?
>
>
> Dirk

Yes. And it used to be true. Certainly one should never use
cli() and sti() so all you have to protect critical sections
from interrupts are spin-locks. This has been broken for some
time so, I suggest you just enable SMP in your .config and
live with it for the time being.

Cheers,
Dick Johnson
Penguin : Linux version 2.6.13.4 on an i686 machine (5589.55 BogoMips).
Warning : 98.36% of all statistics are fiction.
.

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