Michael Ellerman 6772faa1ba powerpc/perf: Fix deadlock caused by calling printk() in PMU exception ... In commit bc09c21 "Fix finding overflowed PMC in interrupt" we added a printk() to the PMU exception handler. Unfortunately that is not safe. The problem is that the PMU exception may run even when interrupts are soft disabled, aka NMI context. We do this so that we can profile parts of the kernel that have interrupts soft-disabled. But by calling printk() from the exception handler, we can potentially deadlock in the printk code on logbuf_lock, eg: [c00000038ba575c0] c000000000081928 .vprintk_emit+0xa8/0x540 [c00000038ba576a0] c0000000007bcde8 .printk+0x48/0x58 [c00000038ba57710] c000000000076504 .perf_event_interrupt+0x2d4/0x490 [c00000038ba57810] c00000000001f6f8 .performance_monitor_exception+0x48/0x60 [c00000038ba57880] c0000000000032cc performance_monitor_common+0x14c/0x180 --- Exception: f01 (Performance Monitor) at c0000000007b25d4 ._raw_spin_lock_irq +0x64/0xc0 [c00000038ba57bf0] c00000000007ed90 .devkmsg_read+0xd0/0x5a0 [c00000038ba57d00] c0000000001c2934 .vfs_read+0xc4/0x1e0 [c00000038ba57d90] c0000000001c2cd8 .SyS_read+0x58/0xd0 [c00000038ba57e30] c000000000009d54 syscall_exit+0x0/0x98 --- Exception: c01 (System Call) at 00001fffffbf6f7c SP (3ffff6d4de10) is in userspace Fix it by making sure we only call printk() when we are not in NMI context. Signed-off-by: Michael Ellerman <michael@ellerman.id.au> Cc: <stable@vger.kernel.org> # 3.9 Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>		2013-06-10 08:36:32 +10:00
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bhrb.S	powerpc/perf: Add basic assembly code to read BHRB entries on POWER8	2013-04-26 16:11:11 +10:00
callchain.c
core-book3s.c	powerpc/perf: Fix deadlock caused by calling printk() in PMU exception	2013-06-10 08:36:32 +10:00
core-fsl-emb.c
e500-pmu.c
Makefile	powerpc/perf: Add basic assembly code to read BHRB entries on POWER8	2013-04-26 16:11:11 +10:00
mpc7450-pmu.c
power4-pmu.c
power5-pmu.c	powerpc/perf: Add an explict flag indicating presence of SLOT field	2013-04-26 16:11:07 +10:00
power5+-pmu.c	powerpc/perf: Add an explict flag indicating presence of SLOT field	2013-04-26 16:11:07 +10:00
power6-pmu.c
power7-pmu.c	perf/POWER7: Create a sysfs format entry for Power7 events	2013-03-13 17:01:04 -03:00
power8-pmu.c	powerpc/perf: Define BHRB generic functions, data and flags for POWER8	2013-04-26 16:13:01 +10:00
ppc970-pmu.c