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

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Invalid values can result in devision-by-zero panics or other
undefined behaviour so lets not allow them.

PR: 221957
Obtained from: ElectroBSD
Submitted by: Fabian Keil
Differential Revision: https://reviews.freebsd.org/D12351
This commit is contained in:
Warner Losh 2017-09-20 21:19:53 +00:00
parent 84c12dcdd0
commit 2d22619adc
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=323829
1 changed files with 24 additions and 3 deletions
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27
sys/cam/cam_iosched.c
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@ -883,6 +883,27 @@ 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)
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)
{
@ -1104,9 +1125,9 @@ 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,