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authorPeter Zijlstra <a.p.zijlstra@chello.nl>2008-02-13 15:33:16 -0500
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2008-02-13 16:29:25 -0500
commitaa02cd2d9bd1e24a230bd66a0a741b984d03915a (patch)
tree06e341e095749048feabbe2ded236e5db38ee251 /arch
parent10270d4838bdc493781f5a1cf2e90e9c34c9142f (diff)
xtime_lock vs update_process_times
Commit d3d74453c34f8fd87674a8cf5b8a327c68f22e99 ("hrtimer: fixup the HRTIMER_CB_IRQSAFE_NO_SOFTIRQ fallback") broke several archs, and since only Russell bothered to merge the fix, and Greg to ACK his arch, I'm sending this for merger. I have confirmation that the Alpha bit results in a booting kernel. That leaves: blackfin, frv, sh and sparc untested. The deadlock in question was found by Russell: IRQ handle -> timer_tick() - xtime seqlock held for write -> update_process_times() -> run_local_timers() -> hrtimer_run_queues() -> hrtimer_get_softirq_time() - tries to get a read lock Now, Thomas assures me the fix is trivial, only do_timer() needs to be done under the xtime_lock, and update_process_times() can savely be removed from under it. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Greg Ungerer <gerg@uclinux.org> CC: Richard Henderson <rth@twiddle.net> CC: Bryan Wu <bryan.wu@analog.com> CC: David Howells <dhowells@redhat.com> CC: Paul Mundt <lethal@linux-sh.org> CC: William Irwin <wli@holomorphy.com> Acked-by: Ingo Molnar <mingo@elte.hu> Acked-by: Ivan Kokshaysky <ink@jurassic.park.msu.ru> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch')
-rw-r--r--arch/alpha/kernel/time.c15
-rw-r--r--arch/blackfin/kernel/time.c8
-rw-r--r--arch/frv/kernel/time.c6
-rw-r--r--arch/m68knommu/kernel/time.c12
-rw-r--r--arch/sh/kernel/timers/timer-cmt.c9
-rw-r--r--arch/sh/kernel/timers/timer-mtu2.c2
-rw-r--r--arch/sparc/kernel/pcic.c2
-rw-r--r--arch/sparc/kernel/time.c7
8 files changed, 28 insertions, 33 deletions
diff --git a/arch/alpha/kernel/time.c b/arch/alpha/kernel/time.c
index 1dd50d07693c..75480cab0893 100644
--- a/arch/alpha/kernel/time.c
+++ b/arch/alpha/kernel/time.c
@@ -119,13 +119,8 @@ irqreturn_t timer_interrupt(int irq, void *dev)
119 state.partial_tick = delta & ((1UL << FIX_SHIFT) - 1); 119 state.partial_tick = delta & ((1UL << FIX_SHIFT) - 1);
120 nticks = delta >> FIX_SHIFT; 120 nticks = delta >> FIX_SHIFT;
121 121
122 while (nticks > 0) { 122 if (nticks)
123 do_timer(1); 123 do_timer(nticks);
124#ifndef CONFIG_SMP
125 update_process_times(user_mode(get_irq_regs()));
126#endif
127 nticks--;
128 }
129 124
130 /* 125 /*
131 * If we have an externally synchronized Linux clock, then update 126 * If we have an externally synchronized Linux clock, then update
@@ -141,6 +136,12 @@ irqreturn_t timer_interrupt(int irq, void *dev)
141 } 136 }
142 137
143 write_sequnlock(&xtime_lock); 138 write_sequnlock(&xtime_lock);
139
140#ifndef CONFIG_SMP
141 while (nticks--)
142 update_process_times(user_mode(get_irq_regs()));
143#endif
144
144 return IRQ_HANDLED; 145 return IRQ_HANDLED;
145} 146}
146 147
diff --git a/arch/blackfin/kernel/time.c b/arch/blackfin/kernel/time.c
index 5bd64e341df3..9bdc8f99183a 100644
--- a/arch/blackfin/kernel/time.c
+++ b/arch/blackfin/kernel/time.c
@@ -137,9 +137,6 @@ irqreturn_t timer_interrupt(int irq, void *dummy)
137 137
138 do_timer(1); 138 do_timer(1);
139 139
140#ifndef CONFIG_SMP
141 update_process_times(user_mode(get_irq_regs()));
142#endif
143 profile_tick(CPU_PROFILING); 140 profile_tick(CPU_PROFILING);
144 141
145 /* 142 /*
@@ -161,6 +158,11 @@ irqreturn_t timer_interrupt(int irq, void *dummy)
161 last_rtc_update = xtime.tv_sec - 600; 158 last_rtc_update = xtime.tv_sec - 600;
162 } 159 }
163 write_sequnlock(&xtime_lock); 160 write_sequnlock(&xtime_lock);
161
162#ifndef CONFIG_SMP
163 update_process_times(user_mode(get_irq_regs()));
164#endif
165
164 return IRQ_HANDLED; 166 return IRQ_HANDLED;
165} 167}
166 168
diff --git a/arch/frv/kernel/time.c b/arch/frv/kernel/time.c
index 925fb0199a0f..69f6a4ef5d61 100644
--- a/arch/frv/kernel/time.c
+++ b/arch/frv/kernel/time.c
@@ -63,6 +63,7 @@ static irqreturn_t timer_interrupt(int irq, void *dummy)
63 /* last time the cmos clock got updated */ 63 /* last time the cmos clock got updated */
64 static long last_rtc_update = 0; 64 static long last_rtc_update = 0;
65 65
66 profile_tick(CPU_PROFILING);
66 /* 67 /*
67 * Here we are in the timer irq handler. We just have irqs locally 68 * Here we are in the timer irq handler. We just have irqs locally
68 * disabled but we don't know if the timer_bh is running on the other 69 * disabled but we don't know if the timer_bh is running on the other
@@ -73,8 +74,6 @@ static irqreturn_t timer_interrupt(int irq, void *dummy)
73 write_seqlock(&xtime_lock); 74 write_seqlock(&xtime_lock);
74 75
75 do_timer(1); 76 do_timer(1);
76 update_process_times(user_mode(get_irq_regs()));
77 profile_tick(CPU_PROFILING);
78 77
79 /* 78 /*
80 * If we have an externally synchronized Linux clock, then update 79 * If we have an externally synchronized Linux clock, then update
@@ -99,6 +98,9 @@ static irqreturn_t timer_interrupt(int irq, void *dummy)
99#endif /* CONFIG_HEARTBEAT */ 98#endif /* CONFIG_HEARTBEAT */
100 99
101 write_sequnlock(&xtime_lock); 100 write_sequnlock(&xtime_lock);
101
102 update_process_times(user_mode(get_irq_regs()));
103
102 return IRQ_HANDLED; 104 return IRQ_HANDLED;
103} 105}
104 106
diff --git a/arch/m68knommu/kernel/time.c b/arch/m68knommu/kernel/time.c
index 89cdbcaeb45f..0ccfb2ad6380 100644
--- a/arch/m68knommu/kernel/time.c
+++ b/arch/m68knommu/kernel/time.c
@@ -42,14 +42,12 @@ irqreturn_t arch_timer_interrupt(int irq, void *dummy)
42 /* last time the cmos clock got updated */ 42 /* last time the cmos clock got updated */
43 static long last_rtc_update=0; 43 static long last_rtc_update=0;
44 44
45 if (current->pid)
46 profile_tick(CPU_PROFILING);
47
45 write_seqlock(&xtime_lock); 48 write_seqlock(&xtime_lock);
46 49
47 do_timer(1); 50 do_timer(1);
48#ifndef CONFIG_SMP
49 update_process_times(user_mode(get_irq_regs()));
50#endif
51 if (current->pid)
52 profile_tick(CPU_PROFILING);
53 51
54 /* 52 /*
55 * If we have an externally synchronized Linux clock, then update 53 * If we have an externally synchronized Linux clock, then update
@@ -67,6 +65,10 @@ irqreturn_t arch_timer_interrupt(int irq, void *dummy)
67 } 65 }
68 66
69 write_sequnlock(&xtime_lock); 67 write_sequnlock(&xtime_lock);
68
69#ifndef CONFIG_SMP
70 update_process_times(user_mode(get_irq_regs()));
71#endif
70 return(IRQ_HANDLED); 72 return(IRQ_HANDLED);
71} 73}
72 74
diff --git a/arch/sh/kernel/timers/timer-cmt.c b/arch/sh/kernel/timers/timer-cmt.c
index 499e07beebe2..71312324b5de 100644
--- a/arch/sh/kernel/timers/timer-cmt.c
+++ b/arch/sh/kernel/timers/timer-cmt.c
@@ -100,16 +100,7 @@ static irqreturn_t cmt_timer_interrupt(int irq, void *dev_id)
100 timer_status &= ~0x80; 100 timer_status &= ~0x80;
101 ctrl_outw(timer_status, CMT_CMCSR_0); 101 ctrl_outw(timer_status, CMT_CMCSR_0);
102 102
103 /*
104 * Here we are in the timer irq handler. We just have irqs locally
105 * disabled but we don't know if the timer_bh is running on the other
106 * CPU. We need to avoid to SMP race with it. NOTE: we don' t need
107 * the irq version of write_lock because as just said we have irq
108 * locally disabled. -arca
109 */
110 write_seqlock(&xtime_lock);
111 handle_timer_tick(); 103 handle_timer_tick();
112 write_sequnlock(&xtime_lock);
113 104
114 return IRQ_HANDLED; 105 return IRQ_HANDLED;
115} 106}
diff --git a/arch/sh/kernel/timers/timer-mtu2.c b/arch/sh/kernel/timers/timer-mtu2.c
index b7499a2a9188..463cd08f9517 100644
--- a/arch/sh/kernel/timers/timer-mtu2.c
+++ b/arch/sh/kernel/timers/timer-mtu2.c
@@ -100,9 +100,7 @@ static irqreturn_t mtu2_timer_interrupt(int irq, void *dev_id)
100 ctrl_outb(timer_status, MTU2_TSR_1); 100 ctrl_outb(timer_status, MTU2_TSR_1);
101 101
102 /* Do timer tick */ 102 /* Do timer tick */
103 write_seqlock(&xtime_lock);
104 handle_timer_tick(); 103 handle_timer_tick();
105 write_sequnlock(&xtime_lock);
106 104
107 return IRQ_HANDLED; 105 return IRQ_HANDLED;
108} 106}
diff --git a/arch/sparc/kernel/pcic.c b/arch/sparc/kernel/pcic.c
index 4cd5d7818dc6..a6a6f9823370 100644
--- a/arch/sparc/kernel/pcic.c
+++ b/arch/sparc/kernel/pcic.c
@@ -713,10 +713,10 @@ static irqreturn_t pcic_timer_handler (int irq, void *h)
713 write_seqlock(&xtime_lock); /* Dummy, to show that we remember */ 713 write_seqlock(&xtime_lock); /* Dummy, to show that we remember */
714 pcic_clear_clock_irq(); 714 pcic_clear_clock_irq();
715 do_timer(1); 715 do_timer(1);
716 write_sequnlock(&xtime_lock);
716#ifndef CONFIG_SMP 717#ifndef CONFIG_SMP
717 update_process_times(user_mode(get_irq_regs())); 718 update_process_times(user_mode(get_irq_regs()));
718#endif 719#endif
719 write_sequnlock(&xtime_lock);
720 return IRQ_HANDLED; 720 return IRQ_HANDLED;
721} 721}
722 722
diff --git a/arch/sparc/kernel/time.c b/arch/sparc/kernel/time.c
index 00b393c3a4a0..cfaf22c05bc4 100644
--- a/arch/sparc/kernel/time.c
+++ b/arch/sparc/kernel/time.c
@@ -128,10 +128,6 @@ irqreturn_t timer_interrupt(int irq, void *dev_id)
128 clear_clock_irq(); 128 clear_clock_irq();
129 129
130 do_timer(1); 130 do_timer(1);
131#ifndef CONFIG_SMP
132 update_process_times(user_mode(get_irq_regs()));
133#endif
134
135 131
136 /* Determine when to update the Mostek clock. */ 132 /* Determine when to update the Mostek clock. */
137 if (ntp_synced() && 133 if (ntp_synced() &&
@@ -145,6 +141,9 @@ irqreturn_t timer_interrupt(int irq, void *dev_id)
145 } 141 }
146 write_sequnlock(&xtime_lock); 142 write_sequnlock(&xtime_lock);
147 143
144#ifndef CONFIG_SMP
145 update_process_times(user_mode(get_irq_regs()));
146#endif
148 return IRQ_HANDLED; 147 return IRQ_HANDLED;
149} 148}
150 149