| Message ID | 20211019101204.4a7m2i3u5uoqrc6b@linutronix.de (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | e22db7bd552f7f7f19fe4ef60abfb7e7b364e3a8 |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [net-next] net: sched: Allow statistics reads from softirq. | expand |
| Context | Check | Description |
|---|---|---|
| netdev/cover_letter | success | Single patches do not need cover letters |
| netdev/fixes_present | success | Fixes tag not required for -next series |
| netdev/patch_count | success | Link |
| netdev/tree_selection | success | Clearly marked for net-next |
| netdev/subject_prefix | success | Link |
| netdev/cc_maintainers | success | CCed 5 of 5 maintainers |
| netdev/source_inline | success | Was 0 now: 0 |
| netdev/verify_signedoff | success | Signed-off-by tag matches author and committer |
| netdev/module_param | success | Was 0 now: 0 |
| netdev/build_32bit | success | Errors and warnings before: 7 this patch: 7 |
| netdev/kdoc | success | Errors and warnings before: 0 this patch: 0 |
| netdev/verify_fixes | success | Fixes tag looks correct |
| netdev/checkpatch | success | total: 0 errors, 0 warnings, 0 checks, 8 lines checked |
| netdev/build_allmodconfig_warn | success | Errors and warnings before: 7 this patch: 7 |
| netdev/header_inline | success | No static functions without inline keyword in header files |
Hello: This patch was applied to netdev/net-next.git (master) by David S. Miller <davem@davemloft.net>: On Tue, 19 Oct 2021 12:12:04 +0200 you wrote: > Eric reported that the rate estimator reads statics from the softirq > which in turn triggers a warning introduced in the statistics rework. > > The warning is too cautious. The updates happen in the softirq context > so reads from softirq are fine since the writes can not be preempted. > The updates/writes happen during qdisc_run() which ensures one writer > and the softirq context. > The remaining bad context for reading statistics remains in hard-IRQ > because it may preempt a writer. > > [...] Here is the summary with links: - [net-next] net: sched: Allow statistics reads from softirq. https://git.kernel.org/netdev/net-next/c/e22db7bd552f You are awesome, thank you! -- Deet-doot-dot, I am a bot. https://korg.docs.kernel.org/patchwork/pwbot.html
diff --git a/net/core/gen_stats.c b/net/core/gen_stats.c index 5516ea0d5da0b..15c270e22c5ef 100644 --- a/net/core/gen_stats.c +++ b/net/core/gen_stats.c @@ -154,7 +154,7 @@ void gnet_stats_add_basic(struct gnet_stats_basic_sync *bstats, u64 bytes = 0; u64 packets = 0; - WARN_ON_ONCE((cpu || running) && !in_task()); + WARN_ON_ONCE((cpu || running) && in_hardirq()); if (cpu) { gnet_stats_add_basic_cpu(bstats, cpu);
Eric reported that the rate estimator reads statics from the softirq which in turn triggers a warning introduced in the statistics rework. The warning is too cautious. The updates happen in the softirq context so reads from softirq are fine since the writes can not be preempted. The updates/writes happen during qdisc_run() which ensures one writer and the softirq context. The remaining bad context for reading statistics remains in hard-IRQ because it may preempt a writer. Fixes: 29cbcd8582837 ("net: sched: Remove Qdisc::running sequence counter") Reported-by: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> --- net/core/gen_stats.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)