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Wed, 4 May 2022 06:52:14 +0000 (GMT) Received: from eusmgms1.samsung.com (unknown [182.198.249.179]) by eusmtrp1.samsung.com (KnoxPortal) with ESMTP id 20220504065214eusmtrp106195fe16407f8ba3fe987d3d4b9290c~r1FFffxUR3149131491eusmtrp1X; Wed, 4 May 2022 06:52:14 +0000 (GMT) X-AuditID: cbfec7f4-45bff7000000269f-91-6272229e2b23 Received: from eusmtip2.samsung.com ( [203.254.199.222]) by eusmgms1.samsung.com (EUCPMTA) with SMTP id 3B.0C.09522.E9222726; Wed, 4 May 2022 07:52:14 +0100 (BST) Received: from [106.210.134.192] (unknown [106.210.134.192]) by eusmtip2.samsung.com (KnoxPortal) with ESMTPA id 20220504065213eusmtip2793e91bcc24acd1c6e86dd5cdb23c1c4~r1FE_Yd6Z3224332243eusmtip2M; Wed, 4 May 2022 06:52:13 +0000 (GMT) Message-ID: <3175262f-5d89-1f57-eb27-9df4d9ad8565@samsung.com> Date: Wed, 4 May 2022 08:52:14 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.8.0 Subject: Re: [PATCH printk v5 1/1] printk: extend console_lock for per-console locking Content-Language: en-US To: John Ogness , Petr Mladek Cc: Sergey Senozhatsky , Steven Rostedt , Thomas Gleixner , linux-kernel@vger.kernel.org, Greg Kroah-Hartman , linux-amlogic@lists.infradead.org From: Marek Szyprowski In-Reply-To: <87pmkton7h.fsf@jogness.linutronix.de> Content-Transfer-Encoding: 7bit X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFlrJKsWRmVeSWpSXmKPExsWy7djP87rzlIqSDH5/VbBoXryezWLblfmM Fgtmc1tc3jWHzeL/46+sFvs6HjBZ7N64iM1i86apzA4cHrMbLrJ4tOy7xe7x7tw5do/9c9ew e2xeUu+xfstVFo/Pm+QC2KO4bFJSczLLUov07RK4MpZO+sFacJa74sTnBUwNjNs4uxg5OSQE TCSmNU1l7GLk4hASWMEoce96GzOE84VRYtPlZywQzmdGidWvFjDBtMzsmgDVspxRYuqGXiYI 5yOjxP0zO9hBqngF7CQmdX4Cs1kEVCSmLTnNCBEXlDg58wkLiC0qkCQxd989oH0cHMICERJt e0NBwswC4hK3nswHWyYi4C2x6vVedpD5zAJfGSUmT/4PNodNwFCi620XG4jNKWAs0Tr5OiNE s7zE9rdzwH6QEHjDIXGqZwMjxNkuEqdb77FB2MISr45vYYewZSROT+5hATlCQiBf4u8MY4hw hcS112uYIWxriTvnfrGBlDALaEqs36UPEXaUmPKrjx2ik0/ixltBiAv4JCZtm84MEeaV6GgT gqhWk5h1fB3czoMXLjFPYFSahRQms5A8PwvJL7MQ9i5gZFnFKJ5aWpybnlpslJdarlecmFtc mpeul5yfu4kRmJpO/zv+ZQfj8lcf9Q4xMnEwHmKU4GBWEuF1XlqQJMSbklhZlVqUH19UmpNa fIhRmoNFSZw3OXNDopBAemJJanZqakFqEUyWiYNTqoHJgCvvqXH9J1ejtMnFgd5/asKunb9k r8n/c5aXQTZnXAaLzvYFS9ntjEU6gxrnz4w0NU/buYMle247j2nyFEUrjbi50hMWL94psfDh o2LR0qeLEtc8kv3yhS/AzSXg22T/E0cn/1m23vlBwG3/29vVrQpYDE4WdsteWcjEJLS8OYXn zR+nC+vaXpxeNP+V6ZStM7z+3bm5RW3O3a6sAIvbCyMeZDFeO/XBsF8s8d7VNyk6RxqaHyoW 60mzfHaL+NrVWvGvaHd0k0zQi2Nz395V3XTrpYKCh9nv5T85Ghfx1r97Vr5xdZ3gtsVGve/d fBYkCCnz71hyK2zq+ZRs6VaR1uY4TuGZjSeDVj+0PtWlxFKckWioxVxUnAgAEoHb+bwDAAA= X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFtrLIsWRmVeSWpSXmKPExsVy+t/xe7rzlIqSDLrvcls0L17PZrHtynxG iwWzuS0u75rDZvH/8VdWi30dD5gsdm9cxGaxedNUZgcOj9kNF1k8WvbdYvd4d+4cu8f+uWvY PTYvqfdYv+Uqi8fnTXIB7FF6NkX5pSWpChn5xSW2StGGFkZ6hpYWekYmlnqGxuaxVkamSvp2 NimpOZllqUX6dgl6GUsn/WAtOMtdceLzAqYGxm2cXYycHBICJhIzuyYwdjFycQgJLGWUON7Z xg6RkJE4Oa2BFcIWlvhzrYsNxBYSeM8osWOVEYjNK2AnManzE1g9i4CKxLQlpxkh4oISJ2c+ YQGxRQWSJF5sew4U5+AQFoiQeN8LFmYWEJe49WQ+E4gtIuAtser1XnaQG5gFvjJKrP3wDOqg t6wSvy62gA1lEzCU6HoLcQSngLFE6+TrjBCTzCS6tnZB2fIS29/OYZ7AKDQLyR2zkCychaRl FpKWBYwsqxhFUkuLc9Nziw31ihNzi0vz0vWS83M3MQLjcduxn5t3MM579VHvECMTB+MhRgkO ZiURXuelBUlCvCmJlVWpRfnxRaU5qcWHGE2BgTGRWUo0OR+YEPJK4g3NDEwNTcwsDUwtzYyV xHk9CzoShQTSE0tSs1NTC1KLYPqYODilGpjkb0hlNR8rmdsWe26R77eWr+tYS5kDAy/8LZhU oGnYveBOhqfXTcH5Dv5FfMEVV1y6nDfnsLiZf5u9YK+ivccXxv9TN1c3/itQUja4nm4oeqvW acKWO+uTPVy0PuUttejTtZilXsqn9YNPsajwqoyWCbOhw9lJ7o6Hw85cNp8WNrciXMb5z72e p9u+8nLpS1cc96x2PhI5P8ZYvEbZ/twulz3q6w+dFC5dtfrPpvZra3k/31z62TzwybV4ZxUD q09R6grcl79MtpPPcUu9GVe00CVXeb5T4GuNewcjKhc2KG1NmMOv2nw4UGxeO//mTNVmG4Fl TFefpTMt173IEvRAPMFCKev68pRtrw0DlFiKMxINtZiLihMB87Pfg1ADAAA= X-CMS-MailID: 20220504065214eucas1p2caed306531082a9d677b4a4a279e4e92 X-Msg-Generator: CA Content-Type: text/plain; charset="utf-8" X-RootMTR: 20220427070833eucas1p27a32ce7c41c0da26f05bd52155f0031c X-EPHeader: CA CMS-TYPE: 201P X-CMS-RootMailID: 20220427070833eucas1p27a32ce7c41c0da26f05bd52155f0031c References: <20220421212250.565456-1-john.ogness@linutronix.de> <20220421212250.565456-15-john.ogness@linutronix.de> <878rrs6ft7.fsf@jogness.linutronix.de> <2a82eae7-a256-f70c-fd82-4e510750906e@samsung.com> <87fslyv6y3.fsf@jogness.linutronix.de> <51dfc4a0-f6cf-092f-109f-a04eeb240655@samsung.com> <87k0b6blz2.fsf@jogness.linutronix.de> <32bba8f8-dec7-78aa-f2e5-f62928412eda@samsung.com> <87y1zkkrjy.fsf@jogness.linutronix.de> <601d6979-7462-6f20-0d60-2fcfcf1e405b@samsung.com> <87pmkton7h.fsf@jogness.linutronix.de> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi John, On 04.05.2022 07:56, John Ogness wrote: > On 2022-05-03, Marek Szyprowski wrote: >>> I suppose if you login via ssh and check /proc/interrupts, then type >>> some things over serial, then check /proc/interrupts again, you will >>> see there have been no interrupts for the uart. But interrupts for >>> other devices are happening. Is this correct? >> Right. The counter for ttyAML0 is not increased when lockup happens >> and I type something to the uart console. > Hmmm. This would imply that the interrupts are disabled fo the UART. > > Just to be sure that we haven't corrupted something in the driver, if > you make the following change, everything works, right? > > --------- BEGIN PATCH ------ > diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c > index c7973266b176..1eaa323e335c 100644 > --- a/kernel/printk/printk.c > +++ b/kernel/printk/printk.c > @@ -3578,7 +3578,7 @@ static int __init printk_activate_kthreads(void) > struct console *con; > > console_lock(); > - printk_kthreads_available = true; > + //printk_kthreads_available = true; > for_each_console(con) > printk_start_kthread(con); > console_unlock(); > --------- END PATCH ------ > > The above change will cause the kthreads to not print and instead always > fallback to the direct method. With the above change console always works. Best regards -- Marek Szyprowski, PhD Samsung R&D Institute Poland