Messages in this thread | | | Date | Mon, 16 May 2011 23:54:24 +0200 | From | Jiri Slaby <> | Subject | Re: [PATCH 2/3] printk: Add %ptc to safely print a task's comm |
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On 05/16/2011 11:19 PM, John Stultz wrote: > Accessing task->comm requires proper locking. However in the past > access to current->comm could be done without locking. This > is no longer the case, so all comm access needs to be done > while holding the comm_lock. > > In my attempt to clean up unprotected comm access, I've noticed > most comm access is done for printk output. To simplify correct > locking in these cases, I've introduced a new %ptc format, > which will print the corresponding task's comm. > > Example use: > printk("%ptc: unaligned epc - sending SIGBUS.\n", current); > > CC: Ted Ts'o <tytso@mit.edu> > CC: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> > CC: David Rientjes <rientjes@google.com> > CC: Dave Hansen <dave@linux.vnet.ibm.com> > CC: Andrew Morton <akpm@linux-foundation.org> > CC: linux-mm@kvack.org > Signed-off-by: John Stultz <john.stultz@linaro.org> > --- > lib/vsprintf.c | 24 ++++++++++++++++++++++++ > 1 files changed, 24 insertions(+), 0 deletions(-) > > diff --git a/lib/vsprintf.c b/lib/vsprintf.c > index bc0ac6b..b7a9953 100644 > --- a/lib/vsprintf.c > +++ b/lib/vsprintf.c > @@ -797,6 +797,23 @@ char *uuid_string(char *buf, char *end, const u8 *addr, > return string(buf, end, uuid, spec); > } > > +static noinline_for_stack
Actually, why noinline? Did your previous version have there some TASK_COMM_LEN buffer or anything on stack which is not there anymore?
> +char *task_comm_string(char *buf, char *end, void *addr, > + struct printf_spec spec, const char *fmt) > +{ > + struct task_struct *tsk = addr; > + char *ret; > + unsigned long flags; > + > + spin_lock_irqsave(&tsk->comm_lock, flags); > + ret = string(buf, end, tsk->comm, spec); > + spin_unlock_irqrestore(&tsk->comm_lock, flags); > + > + return ret; > +} > + > + > + > int kptr_restrict = 1; > > /*
thanks, -- js
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