The first read on an Alea takes about 1.8 seconds, more than the
timeout value waiting for the read. As a consequence, later URB reuse
causes the warning given below. To avoid this, we increase the wait
time for the first read on the Alea.
[ 78.293247] WARNING: CPU: 3 PID: 1892 at drivers/usb/core/urb.c:338 usb_submit_urb+0x2b4/0x580 [usbcore]
[ 78.293250] URB ffff8802135be3c0 submitted while active
[ 78.293252] Modules linked in: chaoskey(+) rng_core rfcomm binfmt_misc bnep cfg80211 nfsd auth_rpcgss oid_registry nfs_acl nfs lockd grace fscache sunrpc bridge stp llc tun snd_hda_codec_hdmi snd_hda_codec_realtek snd_hda_codec_generic iTCO_wdt iTCO_vendor_support nls_utf8 nls_cp437 vfat fat intel_rapl x86_pkg_temp_thermal intel_powerclamp coretemp kvm_intel efi_pstore kvm irqbypass pcspkr btusb btrtl btbcm btintel uvcvideo joydev bluetooth videobuf2_vmalloc videobuf2_memops efivars videobuf2_v4l2 serio_raw i2c_i801 videobuf2_core videodev cdc_mbim media lpc_ich shpchp mfd_core cdc_ncm usbnet mii cdc_wdm cdc_acm evdev snd_hda_intel snd_hda_codec snd_hwdep snd_hda_core i915 snd_pcm snd_timer i2c_algo_bit drm_kms_helper wmi thinkpad_acpi drm nvram mei_me mei snd soundcore rfkill ac battery i2c_core
[ 78.293335] video button tpm_tis tpm fuse parport_pc ppdev lp parport autofs4 ext4 crc16 jbd2 mbcache algif_skcipher af_alg hid_generic usbhid hid dm_crypt dm_mod sg sr_mod cdrom sd_mod crct10dif_pclmul crc32_pclmul crc32c_intel jitterentropy_rng sha256_generic hmac drbg aesni_intel xhci_pci aes_x86_64 ahci glue_helper xhci_hcd ehci_pci lrw libahci gf128mul ablk_helper cryptd libata sdhci_pci psmouse sdhci scsi_mod ehci_hcd mmc_core usbcore usb_common thermal
[ 78.293402] CPU: 3 PID: 1892 Comm: hwrng Not tainted 4.7.0-rc1-linux-14+ #16
[ 78.293405] Hardware name: LENOVO 232577G/232577G, BIOS G2ET92WW (2.52 ) 02/22/2013
[ 78.293408] 0000000000000000 ffffffff812dfa0f ffff8801fa5b3d68 0000000000000000
[ 78.293413] ffffffff81072224 ffff8802135be3c0 ffff8801fa5b3db8 ffff880212e44210
[ 78.293418] 0000000000000040 ffff880209fb32c0 ffff880212e44200 ffffffff8107228f
[ 78.293422] Call Trace:
[ 78.293432] [<ffffffff812dfa0f>] ? dump_stack+0x5c/0x7d
[ 78.293437] [<ffffffff81072224>] ? __warn+0xc4/0xe0
[ 78.293441] [<ffffffff8107228f>] ? warn_slowpath_fmt+0x4f/0x60
[ 78.293451] [<ffffffff810a46a2>] ? enqueue_task_fair+0xcd2/0x1260
[ 78.293463] [<ffffffffa001ec54>] ? usb_submit_urb+0x2b4/0x580 [usbcore]
[ 78.293474] [<ffffffff8140c2e5>] ? __pm_runtime_resume+0x55/0x70
[ 78.293484] [<ffffffffa0825212>] ? _chaoskey_fill+0x132/0x250 [chaoskey]
[ 78.293485] usbcore: registered new interface driver chaoskey
[ 78.293493] [<ffffffff810aed50>] ? wait_woken+0x90/0x90
[ 78.293500] [<ffffffffa06448c0>] ? devm_hwrng_register+0x80/0x80 [rng_core]
[ 78.293505] [<ffffffffa0825907>] ? chaoskey_rng_read+0x127/0x140 [chaoskey]
[ 78.293511] [<ffffffffa06448c0>] ? devm_hwrng_register+0x80/0x80 [rng_core]
[ 78.293515] [<ffffffffa064492e>] ? hwrng_fillfn+0x6e/0x120 [rng_core]
[ 78.293520] [<ffffffff8108fb5f>] ? kthread+0xcf/0xf0
[ 78.293529] [<ffffffff81596d5f>] ? ret_from_fork+0x1f/0x40
[ 78.293535] [<ffffffff8108fa90>] ? kthread_park+0x50/0x50
Signed-off-by: Bob Ham <bob.ham@xxxxxxxxxxxxx>
---
drivers/usb/misc/chaoskey.c | 17 +++++++++++++++--
1 file changed, 15 insertions(+), 2 deletions(-)
diff --git a/drivers/usb/misc/chaoskey.c b/drivers/usb/misc/chaoskey.c
index 9aef46b..6ddd08a 100644
--- a/drivers/usb/misc/chaoskey.c
+++ b/drivers/usb/misc/chaoskey.c
@@ -60,7 +60,8 @@ MODULE_LICENSE("GPL");
#define CHAOSKEY_BUF_LEN 64 /* max size of USB full speed packet */
-#define NAK_TIMEOUT (HZ) /* stall/wait timeout for device */
+#define NAK_TIMEOUT (HZ) /* normal stall/wait timeout */
+#define ALEA_FIRST_TIMEOUT (HZ*3) /* first stall/wait timeout for Alea */
#ifdef CONFIG_USB_DYNAMIC_MINORS
#define USB_CHAOSKEY_MINOR_BASE 0
@@ -88,6 +89,7 @@ struct chaoskey {
int open; /* open count */
bool present; /* device not disconnected */
bool reading; /* ongoing IO */
+ bool reads_started; /* track first read for Alea */
int size; /* size of buf */
int valid; /* bytes of buf read */
int used; /* bytes of buf consumed */
@@ -192,6 +194,9 @@ static int chaoskey_probe(struct usb_interface *interface,
dev->in_ep = in_ep;
+ if (udev->descriptor.idVendor != ALEA_VENDOR_ID)
+ dev->reads_started = 1;
+
dev->size = size;
dev->present = 1;
@@ -361,6 +366,7 @@ static int _chaoskey_fill(struct chaoskey *dev)
{
DEFINE_WAIT(wait);
int result;
+ bool started;
usb_dbg(dev->interface, "fill");
@@ -393,10 +399,17 @@ static int _chaoskey_fill(struct chaoskey *dev)
goto out;
}
+ /* The first read on the Alea takes a little under 2 seconds.
+ * Reads after the first read take only a few microseconds
+ * though. Presumably the entropy-generating circuit needs
+ * time to ramp up. So, we wait longer on the first read.
+ */
+ started = dev->reads_started;
+ dev->reads_started = true;
result = wait_event_interruptible_timeout(
dev->wait_q,
!dev->reading,
- NAK_TIMEOUT);
+ (started ? NAK_TIMEOUT : ALEA_FIRST_TIMEOUT) );
if (result < 0)
goto out;
--
2.1.4
--
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