Re: [Crash-utility] Crash-utility Digest, Vol 179, Issue 4

在 2020年08月13日 16:33, David Wysochanski 写道: > Hi Lianbo > > On Sat, Aug 8, 2020 at 10:46 PM lijiang <lijiang(a)redhat.com&gt; wrote: >> >> 在 2020年08月07日 00:00, crash-utility-request(a)redhat.com 写道: >>> Message: 5 >>> Date: Thu, 6 Aug 2020 09:30:22 -0400 >>> From: Dave Wysochanski <dwysocha(a)redhat.com&gt; >>> To: crash-utility(a)redhat.com >>> Subject: [Crash-utility] [PATCH v3] Fix "log" command when crash is >>> started with "--minimal" option >>> Message-ID: <20200806133022.2127538-1-dwysocha(a)redhat.com&gt; >>> >>> Commit c86250bce29f introduced the useful '-T' option to print the >>> log timestamp in human-readable form. However, this option does >>> not work when crash is invoked with '--minimal' mode, and if tried, >>> crash will spin at 100% and continuously crash at a divide by 0 >>> because machdep->hz == 0. >>> >>> Fix this by disallowing this option in minimal mode. In addition, >>> only calculate the logic to calculate kt->boot_date.tv_sec >>> when this option is enabled. >>> >> Hi, Dave Wysochanski >> >> Thank you for the patch. >> >>> Fixes: c86250bce29f ("Introduction of the "log -T" option...") >>> Signed-off-by: Dave Wysochanski <dwysocha(a)redhat.com&gt; >>> Reviewed-by: Wang Long <w(a)laoqinren.net&gt; >>> Tested-by: Mathias Krause <minipli(a)grsecurity.net&gt; >>> --- >>> kernel.c | 5 ++++- >>> 1 file changed, 4 insertions(+), 1 deletion(-) >>> >>> diff --git a/kernel.c b/kernel.c >>> index 5ed6021..95119f3 100644 >>> --- a/kernel.c >>> +++ b/kernel.c >>> @@ -4939,7 +4939,10 @@ cmd_log(void) >>> if (argerrs) >>> cmd_usage(pc->curcmd, SYNOPSIS); >>> >>> - if (kt->boot_date.tv_sec == 0) { >>> + if (msg_flags & SHOW_LOG_CTIME && pc->flags & MINIMAL_MODE) >>> + error(FATAL, "log: option 'T' not available in minimal mode\n"); >>> + >>> + if (msg_flags & SHOW_LOG_CTIME && kt->boot_date.tv_sec == 0) { >> >> The above two 'if' statements have the same checking condition, would you mind putting them together >> as a statement block? E.g: >> > Sure I can resubmit a fixup of v4 patch once there are no more changes needed. > >> + if (msg_flags & SHOW_LOG_CTIME) { >> + if (pc->flags & MINIMAL_MODE) { >> + error(WARNING, "the option '-T' not available in minimal mode\n"); >> + return; >> + } >> + >> + if (kt->boot_date.tv_sec == 0) { >> ... >> + } >> } >> >> In addition, might it be more reasonable to issue a warning instead of a fatal error? >> > > If you use WARNING it will not fix the infinite loop / CPU spin at > 100%. You have to CTRL-C the crash program to get the prompt back. > So I do not think this is a good idea. > How did you reproduce it? Can you help to confirm if you have applied the correct patch as below? [root@intel-sharkbay-mb-03 crash]# git diff kernel.c diff --git a/kernel.c b/kernel.c index 5ed6021..6375b24 100644 --- a/kernel.c +++ b/kernel.c @@ -4939,13 +4939,20 @@ cmd_log(void) if (argerrs) cmd_usage(pc->curcmd, SYNOPSIS); - if (kt->boot_date.tv_sec == 0) { - ulonglong uptime_jiffies; - ulong uptime_sec; - get_uptime(NULL, &uptime_jiffies); - uptime_sec = (uptime_jiffies)/(ulonglong)machdep->hz; - kt->boot_date.tv_sec = kt->date.tv_sec - uptime_sec; - kt->boot_date.tv_nsec = 0; + if (msg_flags & SHOW_LOG_CTIME) { + if (pc->flags & MINIMAL_MODE) { + error(WARNING, "the option '-T' not available in minimal mode\n"); + return; + } + + if (kt->boot_date.tv_sec == 0) { + ulonglong uptime_jiffies; + ulong uptime_sec; + get_uptime(NULL, &uptime_jiffies); + uptime_sec = (uptime_jiffies)/(ulonglong)machdep->hz; + kt->boot_date.tv_sec = kt->date.tv_sec - uptime_sec; + kt->boot_date.tv_nsec = 0; + } } if (msg_flags & SHOW_LOG_AUDIT) { I didn't see any problems, it's strange, this is my test steps.