diff options
| author | Jason A. Donenfeld <Jason@zx2c4.com> | 2022-10-10 18:06:07 +0300 |
|---|---|---|
| committer | Herbert Xu <herbert@gondor.apana.org.au> | 2022-10-14 14:03:09 +0300 |
| commit | 96cb9d0554457086664d3bd10630b11193d863f1 (patch) | |
| tree | ca4c2cd1bc899901090990c1149ea0fab9cc2d10 /drivers/char | |
| parent | b411b1a0c8bddd470fc8c3457629ac25a168cba0 (diff) | |
| download | linux-96cb9d0554457086664d3bd10630b11193d863f1.tar.xz | |
hwrng: bcm2835 - use hwrng_msleep() instead of cpu_relax()
Rather than busy looping, yield back to the scheduler and sleep for a
bit in the event that there's no data. This should hopefully prevent the
stalls that Mark reported:
<6>[ 3.362859] Freeing initrd memory: 16196K
<3>[ 23.160131] rcu: INFO: rcu_sched self-detected stall on CPU
<3>[ 23.166057] rcu: 0-....: (2099 ticks this GP) idle=03b4/1/0x40000002 softirq=28/28 fqs=1050
<4>[ 23.174895] (t=2101 jiffies g=-1147 q=2353 ncpus=4)
<4>[ 23.180203] CPU: 0 PID: 49 Comm: hwrng Not tainted 6.0.0 #1
<4>[ 23.186125] Hardware name: BCM2835
<4>[ 23.189837] PC is at bcm2835_rng_read+0x30/0x6c
<4>[ 23.194709] LR is at hwrng_fillfn+0x71/0xf4
<4>[ 23.199218] pc : [<c07ccdc8>] lr : [<c07cb841>] psr: 40000033
<4>[ 23.205840] sp : f093df70 ip : 00000000 fp : 00000000
<4>[ 23.211404] r10: c3c7e800 r9 : 00000000 r8 : c17e6b20
<4>[ 23.216968] r7 : c17e6b64 r6 : c18b0a74 r5 : c07ccd99 r4 : c3f171c0
<4>[ 23.223855] r3 : 000fffff r2 : 00000040 r1 : c3c7e800 r0 : c3f171c0
<4>[ 23.230743] Flags: nZcv IRQs on FIQs on Mode SVC_32 ISA Thumb Segment none
<4>[ 23.238426] Control: 50c5387d Table: 0020406a DAC: 00000051
<4>[ 23.244519] CPU: 0 PID: 49 Comm: hwrng Not tainted 6.0.0 #1
Link: https://lore.kernel.org/all/Y0QJLauamRnCDUef@sirena.org.uk/
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Diffstat (limited to 'drivers/char')
| -rw-r--r-- | drivers/char/hw_random/bcm2835-rng.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/char/hw_random/bcm2835-rng.c b/drivers/char/hw_random/bcm2835-rng.c index e7dd457e9b22..e98fcac578d6 100644 --- a/drivers/char/hw_random/bcm2835-rng.c +++ b/drivers/char/hw_random/bcm2835-rng.c @@ -71,7 +71,7 @@ static int bcm2835_rng_read(struct hwrng *rng, void *buf, size_t max, while ((rng_readl(priv, RNG_STATUS) >> 24) == 0) { if (!wait) return 0; - cpu_relax(); + hwrng_msleep(rng, 1000); } num_words = rng_readl(priv, RNG_STATUS) >> 24; |