Attachment 185948 Details for Bug 221957 – cam iosched: Add a handler for the quanta sysctl to enforce valid values

[patch] cam iosched: Add a handler for the quanta sysctl to enforce valid values

0005-cam-iosched-Add-a-handler-for-the-quanta-sysctl-to-en.diff (text/plain), 3.41 KB, created by Fabian Keil on 2017-08-31 10:25:08 UTC

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Creator: Fabian Keil

Created: 2017-08-31 10:25:08 UTC

Size: 3.41 KB

patch

obsolete

>From 60038eac35d496b9ff2be31a855dd294d1af8314 Mon Sep 17 00:00:00 2001
>From: Fabian Keil <fk@fabiankeil.de>
>Date: Thu, 3 Aug 2017 12:53:12 +0200
>Subject: [PATCH 5/8] cam iosched: Add a handler for the quanta sysctl to
> enforce valid values
>
>Invalid values can result in devision-by-zero panics and other
>undesirable behaviour.
>
>Example panic:
>
>   Fatal trap 18: integer divide fault while in kernel mode
>   cpuid = 0; apic id = 00
>   instruction pointer     = 0x20:0xffffffff802998e5
>   stack pointer           = 0x28:0xfffffe01ea3bf8d0
>   frame pointer           = 0x28:0xfffffe01ea3bf900
>   code segment            = base 0x0, limit 0xfffff, type 0x1b
>                           = DPL 0, pres 1, long 1, def32 0, gran 1
>   processor eflags        = interrupt enabled, resume, IOPL = 0
>   current process         = 12 (swi4: clock (0))
>   trap number             = 18
>   panic: integer divide fault
>   cpuid = 0
>   KDB: stack backtrace:
>   db_trace_self_wrapper() at db_trace_self_wrapper+0x2b/frame 0xfffffe01ea3bf510
>   vpanic() at vpanic+0x186/frame 0xfffffe01ea3bf590
>   panic() at panic+0x43/frame 0xfffffe01ea3bf5f0
>   trap_fatal() at trap_fatal+0x322/frame 0xfffffe01ea3bf640
>   trap() at trap+0x5e/frame 0xfffffe01ea3bf800
>   calltrap() at calltrap+0x8/frame 0xfffffe01ea3bf800
>   --- trap 0x12, rip = 0xffffffff802998e5, rsp = 0xfffffe01ea3bf8d0, rbp = 0xfffffe01ea3bf900 ---
>   cam_iosched_ticker() at cam_iosched_ticker+0x25/frame 0xfffffe01ea3bf900
>   softclock_call_cc() at softclock_call_cc+0x13e/frame 0xfffffe01ea3bf9b0
>   softclock() at softclock+0xb9/frame 0xfffffe01ea3bf9e0
>   intr_event_execute_handlers() at intr_event_execute_handlers+0xec/frame 0xfffffe01ea3bfa20
>   ithread_loop() at ithread_loop+0xd6/frame 0xfffffe01ea3bfa70
>   fork_exit() at fork_exit+0x85/frame 0xfffffe01ea3bfab0
>   fork_trampoline() at fork_trampoline+0xe/frame 0xfffffe01ea3bfab0
>   --- trap 0, rip = 0, rsp = 0, rbp = 0 ---
>   Uptime: 2h29m20s
>   Dumping 1165 out of 8055 MB:..2%..11%..21%..31%..42%..51%..61%..71%..81%..91%
>
>Obtained from: ElectroBSD
>---
> sys/cam/cam_iosched.c | 28 +++++++++++++++++++++++++---
> 1 file changed, 25 insertions(+), 3 deletions(-)
>
>diff --git a/sys/cam/cam_iosched.c b/sys/cam/cam_iosched.c
>index f2e69d9fd84c..7f04db03352e 100644
>--- a/sys/cam/cam_iosched.c
>+++ b/sys/cam/cam_iosched.c
>@@ -880,6 +880,28 @@ cam_iosched_sysctl_latencies(SYSCTL_HANDLER_ARGS)
> 	return (error);
> }
> 
>+static int
>+cam_iosched_quanta_sysctl(SYSCTL_HANDLER_ARGS)
>+{
>+	int *quanta;
>+	int error, value;
>+
>+	quanta = (unsigned *)arg1;
>+	value = *quanta;
>+
>+	error = sysctl_handle_int(oidp, (int *)&value, 0, req);
>+	if ((error != 0) || (req->newptr == NULL))
>+		return (error);
>+
>+	if (value < 1 || value > hz) {
>+		printf("cam iosched: Quanta has to be above 0 and below %d (kern.hz).\n", hz);
>+		return (EINVAL);
>+	}
>+	*quanta = value;
>+
>+	return (0);
>+}
>+
> static void
> cam_iosched_iop_stats_sysctl_init(struct cam_iosched_softc *isc, struct iop_stats *ios, char *name)
> {
>@@ -1101,9 +1123,9 @@ void cam_iosched_sysctl_init(struct cam_iosched_softc *isc,
> 	    &isc->read_bias, 100,
> 	    "How biased towards read should we be independent of limits");
> 
>-	SYSCTL_ADD_INT(ctx, n,
>-	    OID_AUTO, "quanta", CTLFLAG_RW,
>-	    &isc->quanta, 200,
>+	SYSCTL_ADD_PROC(ctx, n,
>+	    OID_AUTO, "quanta", CTLTYPE_UINT | CTLFLAG_RW,
>+	    &isc->quanta, 0, cam_iosched_quanta_sysctl, "I",
> 	    "How many quanta per second do we slice the I/O up into");
> 
> 	SYSCTL_ADD_INT(ctx, n,
>-- 
>2.14.1
>

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Attachments on bug 221957: 185948