[patch V1.1 11/38] misc: sgi-gru: Remove get_cycles() [ab]use

Thomas Gleixner
2026-04-10T20:56:16Z

Calculating a timeout from get_cycles() is a historical leftover without
any functional requirement.

Use ktime_get() instead.

Signed-off-by: Thomas Gleixner <tglx@kernel.org>
---
V2: Fix typo
---
drivers/misc/sgi-gru/gruhandles.c | 20 ++++++++------------
drivers/misc/sgi-gru/grukservices.c | 3 ++-
drivers/misc/sgi-gru/grutlbpurge.c | 5 ++---
3 files changed, 12 insertions(+), 16 deletions(-)

--- a/drivers/misc/sgi-gru/gruhandles.c
+++ b/drivers/misc/sgi-gru/gruhandles.c
@@ -6,26 +6,22 @@
*/

#include <linux/kernel.h>
+#include <linux/timekeeping.h>
#include "gru.h"
#include "grulib.h"
#include "grutables.h"

-/* 10 sec */
#include <linux/sync_core.h>
-#include <asm/tsc.h>
-#define GRU_OPERATION_TIMEOUT ((cycles_t) tsc_khz*10*1000)
-#define CLKS2NSEC(c) ((c) * 1000000 / tsc_khz)
+
+#define GRU_OPERATION_TIMEOUT_NSEC (((ktime_t)10 * NSEC_PER_SEC))

/* Extract the status field from a kernel handle */
#define GET_MSEG_HANDLE_STATUS(h) (((*(unsigned long *)(h)) >> 16) & 3)

struct mcs_op_statistic mcs_op_statistics[mcsop_last];

-static void update_mcs_stats(enum mcs_op op, unsigned long clks)
+static void update_mcs_stats(enum mcs_op op, unsigned long nsec)
{
- unsigned long nsec;
-
- nsec = CLKS2NSEC(clks);
atomic_long_inc(&mcs_op_statistics[op].count);
atomic_long_add(nsec, &mcs_op_statistics[op].total);
if (mcs_op_statistics[op].max < nsec)
@@ -58,21 +54,21 @@ static void report_instruction_timeout(v

static int wait_instruction_complete(void *h, enum mcs_op opc)
{
+ ktime_t start_time = ktime_get();
int status;
- unsigned long start_time = get_cycles();

while (1) {
cpu_relax();
status = GET_MSEG_HANDLE_STATUS(h);
if (status != CCHSTATUS_ACTIVE)
break;
- if (GRU_OPERATION_TIMEOUT < (get_cycles() - start_time)) {
+ if (GRU_OPERATION_TIMEOUT_NSEC < (ktime_get() - start_time)) {
report_instruction_timeout(h);
- start_time = get_cycles();
+ start_time = ktime_get();
}
}
if (gru_options & OPT_STATS)
- update_mcs_stats(opc, get_cycles() - start_time);
+ update_mcs_stats(opc, (unsigned long)(ktime_get() - start_time));
return status;
}

--- a/drivers/misc/sgi-gru/grukservices.c
+++ b/drivers/misc/sgi-gru/grukservices.c
@@ -20,6 +20,7 @@
#include <linux/uaccess.h>
#include <linux/delay.h>
#include <linux/export.h>
+#include <linux/random.h>
#include <asm/io_apic.h>
#include "gru.h"
#include "grulib.h"
@@ -1106,7 +1107,7 @@ static int quicktest3(unsigned long arg)
int ret = 0;

memset(buf2, 0, sizeof(buf2));
- memset(buf1, get_cycles() & 255, sizeof(buf1));
+ memset(buf1, get_random_u32() & 255, sizeof(buf1));
gru_copy_gpa(uv_gpa(buf2), uv_gpa(buf1), BUFSIZE);
if (memcmp(buf1, buf2, BUFSIZE)) {
printk(KERN_DEBUG "GRU:%d quicktest3 error\n", smp_processor_id());
--- a/drivers/misc/sgi-gru/grutlbpurge.c
+++ b/drivers/misc/sgi-gru/grutlbpurge.c
@@ -22,13 +22,12 @@
#include <linux/delay.h>
#include <linux/timex.h>
#include <linux/srcu.h>
+#include <linux/random.h>
#include <asm/processor.h>
#include "gru.h"
#include "grutables.h"
#include <asm/uv/uv_hub.h>

-#define gru_random() get_cycles()
-
/* ---------------------------------- TLB Invalidation functions --------
* get_tgh_handle
*
@@ -49,7 +48,7 @@ static inline int get_off_blade_tgh(stru
int n;

n = GRU_NUM_TGH - gru->gs_tgh_first_remote;
- n = gru_random() % n;
+ n = get_random_u32() % n;
n += gru->gs_tgh_first_remote;
return n;
}