Hi Nishanth, Thanks for reviewing this patch. On Mon, Apr 15, 2013 at 7:40 PM, Nishanth Menon <nm@xxxxxx> wrote: > Daniel, > On Mon, Apr 15, 2013 at 1:24 AM, Amit Daniel Kachhap > <amit.daniel@xxxxxxxxxxx> wrote: >> As per the OPP library documentation(Documentation/power/opp.txt) all >> opp find/get calls should be protected by rcu locks. >> >> Signed-off-by: Amit Daniel Kachhap <amit.daniel@xxxxxxxxxxx> >> --- >> >> This patch is created against linux-next tree and is suggested by >> Nishanth Menon. (https://lkml.org/lkml/2013/4/12/119) >> >> drivers/cpufreq/exynos5440-cpufreq.c | 3 +++ >> 1 files changed, 3 insertions(+), 0 deletions(-) >> >> diff --git a/drivers/cpufreq/exynos5440-cpufreq.c b/drivers/cpufreq/exynos5440-cpufreq.c >> index ead7ed4..0c74018 100644 >> --- a/drivers/cpufreq/exynos5440-cpufreq.c >> +++ b/drivers/cpufreq/exynos5440-cpufreq.c >> @@ -120,11 +120,13 @@ static int init_div_table(void) >> int i = 0; >> struct opp *opp; >> >> + rcu_read_lock(); >> for (i = 0; freq_tbl[i].frequency != CPUFREQ_TABLE_END; i++) { >> >> opp = opp_find_freq_exact(dvfs_info->dev, >> freq_tbl[i].frequency * 1000, true); >> if (IS_ERR(opp)) { >> + rcu_read_unlock(); >> dev_err(dvfs_info->dev, >> "failed to find valid OPP for %u KHZ\n", >> freq_tbl[i].frequency); >> @@ -159,6 +161,7 @@ static int init_div_table(void) >> __raw_writel(tmp, dvfs_info->base + XMU_PMU_P0_7 + 4 * i); >> } >> >> + rcu_read_unlock(); > > Is it not possible to reduce the amount of code protected by RCU lock? > something like this: Yes it is possible but then this part of code is a loop of max 8 iteration so rcu_read_lock will be called those many times. Also this code blocks are just register writes and not doing any time consuming operations. Thanks, Amit Daniel > + rcu_read_lock(); > opp = opp_find_freq_exact(dvfs_info->dev, > freq_tbl[i].frequency * 1000, true); > if (IS_ERR(opp)) { > + rcu_read_unlock(); > dev_err(dvfs_info->dev, > "failed to find valid OPP for %u KHZ\n", > freq_tbl[i].frequency); > return PTR_ERR(opp); > } > + volt_id = opp_get_voltage(opp); > + rcu_unlock(); > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@xxxxxxxxxxxxxxxxxxx > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel -- To unsubscribe from this list: send the line "unsubscribe cpufreq" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
