Eric Lee / smarc-ti-linux-kernel

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Commit 4b7e0706620e3947dc1685dfdbc1413404afb545

Authored by Martin Schwidefsky
Committed by Linus Torvalds
1 parent b2c6678c85
Exists in master and in 20 other branches dlt-processor-sdk-linux-03.00.00.04, newt-ti-linux-3.12.y, processor-sdk-linux-01.00.00, processor-sdk-linux-02.00.01, smarc-ti-linux-3.12.10, smarc-ti-linux-3.12.y, smarc-ti-linux-3.14.y, smarc-ti-linux-3.15.y, smarc-ti-lsk-linux-4.1.y, smarct3x-processor-sdk-04.01.00.06, smarct3x-processor-sdk-linux-02.00.01, smarct3x-processor-sdk-linux-03.00.00.04, smarct4x-800-processor-sdk-linux-02.00.01, smarct4x-processor-sdk-04.01.00.06, smarct4x-processor-sdk-linux-02.00.01, smarct4x-processor-sdk-linux-03.00.00.04, ti-linux-3.12.y, ti-linux-3.14.y, ti-linux-3.15.y, ti-lsk-linux-4.1.y

[PATCH] s390: idle timer setup 

Fix overflow in calculation of the new tod value in stop_hz_timer and fix
wrong virtual timer list idle time in case the virtual timer is already
expired in stop_cpu_timer.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

Showing 2 changed files with 22 additions and 15 deletions Side-by-side Diff

arch/s390/kernel/time.c
Diff comments   View file @ 4b7e070
... ... @@ -244,7 +244,7 @@
244 244 */
245 245 static inline void stop_hz_timer(void)
246 246 {
247   - __u64 timer;
  247 + __u64 timer, todval;
248 248  
249 249 if (sysctl_hz_timer != 0)
250 250 return;
... ... @@ -265,8 +265,14 @@
265 265 * for the next event.
266 266 */
267 267 timer = (__u64) (next_timer_interrupt() - jiffies) + jiffies_64;
268   - timer = jiffies_timer_cc + timer * CLK_TICKS_PER_JIFFY;
269   - asm volatile ("SCKC %0" : : "m" (timer));
  268 + todval = -1ULL;
  269 + /* Be careful about overflows. */
  270 + if (timer < (-1ULL / CLK_TICKS_PER_JIFFY)) {
  271 + timer = jiffies_timer_cc + timer * CLK_TICKS_PER_JIFFY;
  272 + if (timer >= jiffies_timer_cc)
  273 + todval = timer;
  274 + }
  275 + asm volatile ("SCKC %0" : : "m" (todval));
270 276 }
271 277  
272 278 /*
arch/s390/kernel/vtime.c
Diff comments   View file @ 4b7e070
... ... @@ -122,12 +122,17 @@
122 122 struct vtimer_queue *vt_list;
123 123  
124 124 vt_list = &per_cpu(virt_cpu_timer, smp_processor_id());
125   - set_vtimer(vt_list->idle);
  125 +
  126 + /* CPU timer interrupt is pending, don't reprogramm it */
  127 + if (vt_list->idle & 1LL<<63)
  128 + return;
  129 +
  130 + if (!list_empty(&vt_list->list))
  131 + set_vtimer(vt_list->idle);
126 132 }
127 133  
128 134 static void stop_cpu_timer(void)
129 135 {
130   - __u64 done;
131 136 struct vtimer_queue *vt_list;
132 137  
133 138 vt_list = &per_cpu(virt_cpu_timer, smp_processor_id());
134 139  
135 140  
136 141  
137 142  
... ... @@ -138,21 +143,17 @@
138 143 goto fire;
139 144 }
140 145  
141   - /* store progress */
142   - asm volatile ("STPT %0" : "=m" (done));
  146 + /* store the actual expire value */
  147 + asm volatile ("STPT %0" : "=m" (vt_list->idle));
143 148  
144 149 /*
145   - * If done is negative we do not stop the CPU timer
146   - * because we will get instantly an interrupt that
147   - * will start the CPU timer again.
  150 + * If the CPU timer is negative we don't reprogramm
  151 + * it because we will get instantly an interrupt.
148 152 */
149   - if (done & 1LL<<63)
  153 + if (vt_list->idle & 1LL<<63)
150 154 return;
151   - else
152   - vt_list->offset += vt_list->to_expire - done;
153 155  
154   - /* save the actual expire value */
155   - vt_list->idle = done;
  156 + vt_list->offset += vt_list->to_expire - vt_list->idle;
156 157  
157 158 /*
158 159 * We cannot halt the CPU timer, we just write a value that