Re: next-20090310: ext4 hangs

From: Jan Kara
Date: Wed Mar 25 2009 - 20:00:51 EST


Hi,

thanks for the updated disassembly.

> 55bab0: 82 10 60 01 or %g1, 1, %g1
> spin_unlock(&journal->j_list_lock);
> 55bab4: 40 06 4b 20 call 6ee734 <_spin_unlock>
> 55bab8: c2 24 e0 28 st %g1, [ %l3 + 0x28 ]
OK, so it really seems that:
jinode->i_flags |= JI_COMMIT_RUNNING;
spin_unlock(&journal->j_list_lock);

has been compiled to
ld [ %l3 + 0x28 ], %g1
or %g1, 1, %g1
call 6ee734 <_spin_unlock>
st %g1, [ %l3 + 0x28 ]

Which seems like a bug in the compiler or in the way implement compiler
barriers in spin_unlock() on UP sparc. Or is there some sparc magic by which
this is correct code? Any clever sparc guy?

Honza
--
Jan Kara <jack@xxxxxxx>
SUSE Labs, CR
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