| Date | Tue, 30 Mar 2010 15:55:10 -0700 | From | Greg KH <> | Subject | [032/116] [PATCH] sparc64: Make prom entry spinlock NMI safe. |
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2.6.32-stable review patch. If anyone has any objections, please let us know.
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From: David S. Miller <davem@davemloft.net>
[ Upstream commit 8a4fd1e4922413cfdfa6c51a59efb720d904a5eb ]
If we do something like try to print to the OF console from an NMI while we're already in OpenFirmware, we'll deadlock on the spinlock.
Use a raw spinlock and disable NMIs when we take it.
Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
--- arch/sparc/prom/p1275.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-)
--- a/arch/sparc/prom/p1275.c +++ b/arch/sparc/prom/p1275.c @@ -32,8 +32,7 @@ extern void prom_cif_interface(void); extern void prom_cif_callback(void); /* - * This provides SMP safety on the p1275buf. prom_callback() drops this lock - * to allow recursuve acquisition. + * This provides SMP safety on the p1275buf. */ DEFINE_SPINLOCK(prom_entry_lock); @@ -47,7 +46,9 @@ long p1275_cmd(const char *service, long p = p1275buf.prom_buffer; - spin_lock_irqsave(&prom_entry_lock, flags); + raw_local_save_flags(flags); + raw_local_irq_restore(PIL_NMI); + spin_lock(&prom_entry_lock); p1275buf.prom_args[0] = (unsigned long)p; /* service */ strcpy (p, service); @@ -139,7 +140,8 @@ long p1275_cmd(const char *service, long va_end(list); x = p1275buf.prom_args [nargs + 3]; - spin_unlock_irqrestore(&prom_entry_lock, flags); + spin_unlock(&prom_entry_lock); + raw_local_irq_restore(flags); return x; }
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