lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Message-ID: <20190411103844.GA8267@osadl.at> Date: Thu, 11 Apr 2019 12:38:44 +0200 From: Nicholas Mc Guire <der.herr@...r.at> To: Ulf Hansson <ulf.hansson@...aro.org> Cc: Nicholas Mc Guire <hofrat@...ntech.at>, Michael Turquette <mturquette@...libre.com>, Stephen Boyd <sboyd@...nel.org>, Linux ARM <linux-arm-kernel@...ts.infradead.org>, linux-clk <linux-clk@...r.kernel.org>, Linux Kernel Mailing List <linux-kernel@...r.kernel.org> Subject: Re: [PATCH RFC] clk: ux500: add range to usleep_range On Thu, Apr 11, 2019 at 11:36:45AM +0200, Ulf Hansson wrote: > On Sun, 7 Apr 2019 at 05:13, Nicholas Mc Guire <hofrat@...ntech.at> wrote: > > > > Providing a range for usleep_range() allows the hrtimer subsystem to > > coalesce timers - the delay is runtime configurable so a factor 2 > > is taken to provide the range. > > > > Signed-off-by: Nicholas Mc Guire <hofrat@...ntech.at> > > --- > > > > Problem located with an experimental coccinelle script > > > > Q: Basically usleep_range() with min == max never makes much sense notably > > in non-atomic context. If the factor of 2 is tolerable or a fixed > > offset of e.g. 1000 would be more suitable is not clear to me - maybe > > someone familiar with that driver can clarify this. > > > > Patch was compile tested with: u8500_defconfig (implies COMMON_CLK=y) > > (with some sparse warnings about not implemented system calls) > > > > Patch is against 5.1-rc3 (localversion-next is next=20190405) > > > > drivers/clk/ux500/clk-sysctrl.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/drivers/clk/ux500/clk-sysctrl.c b/drivers/clk/ux500/clk-sysctrl.c > > index 7c0403b..a1fa3fb 100644 > > --- a/drivers/clk/ux500/clk-sysctrl.c > > +++ b/drivers/clk/ux500/clk-sysctrl.c > > @@ -42,7 +42,7 @@ static int clk_sysctrl_prepare(struct clk_hw *hw) > > clk->reg_bits[0]); > > > > if (!ret && clk->enable_delay_us) > > - usleep_range(clk->enable_delay_us, clk->enable_delay_us); > > + usleep_range(clk->enable_delay_us, clk->enable_delay_us*2); > > The range being used is actually in ms, so not sure we actually need > to double it for the range. > > How about adding ~25% instead, along the lines of below: > usleep_range(clk->enable_delay_us, clk->enable_delay_us + > (clk->enable_delay_us >> 2)); > that would be perfectly sufficient for hrtimers - if the range is in ms - so I´ll send out a V2 shortly. thx! hofrat
Powered by blists - more mailing lists