Messages in this thread | | | Date | Fri, 8 Jan 2016 07:19:32 +1100 | From | Stephen Rothwell <> | Subject | Re: linux-next: build failure after merge of the rcu tree |
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Hi Paul,
On Thu, 7 Jan 2016 10:02:44 -0800 "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> wrote: > > On Thu, Jan 07, 2016 at 07:57:25PM +1100, Stephen Rothwell wrote: > > Hi Paul, > > > > [I found this a few days ago, but I think I forgot to send the email, > > sorry.] > > > > After merging the rcu tree, today's linux-next build (powerpc > > allyesconfig) failed like this: > > > > kernel/rcu/rcuperf.o:(.discard+0x0): multiple definition of `__pcpu_unique_srcu_ctl_srcu_array' > > kernel/rcu/rcutorture.o:(.discard+0x0): first defined here > > > > Caused by commit > > > > abcd7ec0808e ("rcutorture: Add RCU grace-period performance tests") > > > > I have reverted that commit for today. > > Hello, Stephen, > > Very strange. The "static" keyword does not mean anything here? > Easy enough to use different symbols in the two different files, > but this situation is not so good for information hiding. > > Happy to update rcuperf.c to use a different name, but in the > immortal words of MSDOS, "Are you sure?" :-)
I have no idea why it happens, but I do get the error above unless I revert that commit. So, yes, I am sure :-)
OK, I looked further and
DEFINE_STATIC_SRCU(srcu_ctl);
becomes this (NLs added for clarity):
static __attribute__((section(".discard"), unused)) char __pcpu_scope_srcu_ctl_srcu_array; extern __attribute__((section(".discard"), unused)) char __pcpu_unique_srcu_ctl_srcu_array; __attribute__((section(".discard"), unused)) char __pcpu_unique_srcu_ctl_srcu_array; extern __attribute__((section(".data..percpu" ""))) __typeof__(struct srcu_struct_array) srcu_ctl_srcu_array; __attribute__((section(".data..percpu" ""))) __attribute__((weak)) __typeof__(struct srcu_struct_array) srcu_ctl_srcu_array; static struct srcu_struct srcu_ctl = { . . };
So, the "static" is not very effective :-(
-- Cheers, Stephen Rothwell sfr@canb.auug.org.au
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