Messages in this thread Patch in this message | | | Date | Mon, 6 Feb 2017 10:48:46 +0900 | From | Sergey Senozhatsky <> | Subject | Re: [PATCHv7 4/8] printk: always use deferred printk when flush printk_safe lines |
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On (02/03/17 12:18), Petr Mladek wrote: [..] > > by "the new approved variant" do you mean resend of the entire > > patch set (v8) or just 0004 patch? > > I depends on how many and how complicated are possible conflicts > with the followup patches. > > It is perfectly fine to send just 0004 if there are no conflicts > or if they are trivial to resolve.
so there are no conflicts at all. 0004 can be replaced with the patch below. but the thing is - I want to keep printk_safe_flush_line() around.
we call
static void printk_safe_flush_line(const char *text, int len) { /* * Avoid any console drivers calls from here, because we may be * in NMI or printk_safe context (when in panic). The messages * must go only into the ring buffer at this stage. Consoles will * get explicitly called later when a crashdump is not generated. */ printk_deferred("%.*s", len, text); }
from many places:
4x printk_safe_flush_buffer() 1x __printk_safe_flush()
replacing printk_safe_flush_line() with printk_deferred() produces things like these
printk_deferred("%.*s", end - start, start); printk_deferred("%.*s", strlen(newline), newline);
which, I think, makes the code worse. any objections?
just in case, the patch (which I prefer to be ignored)
===8<======8<===
From daa9bd8c2659a91036c00e22bb218be6871a371d Mon Sep 17 00:00:00 2001 From: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Date: Tue, 27 Dec 2016 23:16:07 +0900 Subject: [PATCH] printk: always use deferred printk when flush printk_safe lines
Always use printk_deferred() in printk_safe_flush_line(). Flushing can be done from NMI or printk_safe contexts (when we are in panic), so we can't call console drivers, yet still want to store the messages in the logbuf buffer. Therefore we use a deferred printk version.
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Suggested-by: Petr Mladek <pmladek@suse.com> --- kernel/printk/printk_safe.c | 30 ++++++++++++------------------ 1 file changed, 12 insertions(+), 18 deletions(-)
diff --git a/kernel/printk/printk_safe.c b/kernel/printk/printk_safe.c index efc89a4e9df5..801f0f1c7547 100644 --- a/kernel/printk/printk_safe.c +++ b/kernel/printk/printk_safe.c @@ -110,19 +110,6 @@ static int printk_safe_log_store(struct printk_safe_seq_buf *s, return add; } -static void printk_safe_flush_line(const char *text, int len) -{ - /* - * The buffers are flushed in NMI only on panic. The messages must - * go only into the ring buffer at this stage. Consoles will get - * explicitly called later when a crashdump is not generated. - */ - if (in_nmi()) - printk_deferred("%.*s", len, text); - else - printk("%.*s", len, text); -} - /* printk part of the temporary buffer line by line */ static int printk_safe_flush_buffer(const char *start, size_t len) { @@ -136,7 +123,14 @@ static int printk_safe_flush_buffer(const char *start, size_t len) /* Print line by line. */ while (c < end) { if (*c == '\n') { - printk_safe_flush_line(start, c - start + 1); + /* + * Avoid any console drivers calls from here, because + * we may be in NMI or printk_safe context (when in + * panic). The messages must go only into the ring + * buffer at this stage. Consoles will get explicitly + * called later when a crashdump is not generated. + */ + printk_deferred("%.*s", c - start + 1, start); start = ++c; header = true; continue; @@ -149,7 +143,7 @@ static int printk_safe_flush_buffer(const char *start, size_t len) continue; } - printk_safe_flush_line(start, c - start); + printk_deferred("%.*s", c - start, start); start = c++; header = true; continue; @@ -163,8 +157,8 @@ static int printk_safe_flush_buffer(const char *start, size_t len) if (start < end && !header) { static const char newline[] = KERN_CONT "\n"; - printk_safe_flush_line(start, end - start); - printk_safe_flush_line(newline, strlen(newline)); + printk_deferred("%.*s", end - start, start); + printk_deferred("%.*s", strlen(newline), newline); } return len; @@ -206,7 +200,7 @@ static void __printk_safe_flush(struct irq_work *work) if ((i && i >= len) || len > sizeof(s->buffer)) { const char *msg = "printk_safe_flush: internal error\n"; - printk_safe_flush_line(msg, strlen(msg)); + printk_deferred("%.*s", strlen(msg), msg); len = 0; } -- 2.11.1
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