mainlining shenanigans
cb10b0f91c
Sebastian Andrzej Siewior says: ==================== net: u64_stats fixups for 32bit. while looking at the u64-stats patch https://lore.kernel.org/all/20220817162703.728679-10-bigeasy@linutronix.de I noticed that u64_stats_fetch_begin() is used. That suspicious thing about it is that network processing, including stats update, is performed in NAPI and so I would expect to see u64_stats_fetch_begin_irq() in order to avoid updates from NAPI during the read. This is only needed on 32bit-UP where the seqcount is not used. This is address in 2/2. The remaining user take some kind of precaution and may use u64_stats_fetch_begin(). I updated the previously mentioned patch to get rid of u64_stats_fetch_begin_irq(). If this is not considered stable patch worthy then it can be ignored and considred fixed by the other series which removes the special 32bit cases. The xrs700x driver reads and writes the counter from preemptible context so the only missing piece here is at least disable preemption on the writer side to avoid preemption while the writer is in progress. The possible reader would spin then until the writer completes its write critical section which is considered bad. This is addressed in 1/2 by using u64_stats_update_begin_irqsave() and so disable interrupts during the write critical section. The other closet resemblance I found is mdio_bus.c::mdiobus_stats_acct() where preemtion is disabled unconditionally. This is something I want to avoid since it also affects 64bit. ==================== Signed-off-by: David S. Miller <davem@davemloft.net> |
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Linux kernel
============
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