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Groups > linux.kernel > #1289426 > unrolled thread
| Started by | Minfei Huang <mnfhuang@gmail.com> |
|---|---|
| First post | 2015-12-11 12:00 +0100 |
| Last post | 2015-12-11 15:50 +0100 |
| Articles | 3 — 2 participants |
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Some confusion about the period of updating new function in Minfei Huang <mnfhuang@gmail.com> - 2015-12-11 12:00 +0100
Re: Some confusion about the period of updating new function in Steven Rostedt <rostedt@goodmis.org> - 2015-12-11 15:30 +0100
Re: Some confusion about the period of updating new function in ftrace Minfei Huang <mnfhuang@gmail.com> - 2015-12-11 15:50 +0100
| From | Minfei Huang <mnfhuang@gmail.com> |
|---|---|
| Date | 2015-12-11 12:00 +0100 |
| Subject | Some confusion about the period of updating new function in |
| Message-ID | <qEtAC-38W-7@gated-at.bofh.it> |
ftrace Reply-To: Hi, Steven. There is a confusion which blocks my step to go further for ftrace. Does ftrace guarantee that the replaced function is finished while ftrace is replacing the functions? In the other word, is there a possible that new function starts to run, while old function is also running (maybe this function is called before replacing the function). Function schedule_on_each_cpu maybe fails to excute, if there is no enough memory to be allocated? Then kernel may be unstable, if ftrace continues, without handling the error, does it? Previously, I posted a patch to fix this issue, and you nacked it. [PATCH] workqueue: Add the allocation flags to function schedule_on_each_cpu_gfp Thanks Minfei -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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| From | Steven Rostedt <rostedt@goodmis.org> |
|---|---|
| Date | 2015-12-11 15:30 +0100 |
| Message-ID | <qEwRQ-5G2-17@gated-at.bofh.it> |
| In reply to | #1289426 |
On Fri, 11 Dec 2015 18:52:42 +0800 Minfei Huang <mnfhuang@gmail.com> wrote: > ftrace > Reply-To: > > Hi, Steven. > > There is a confusion which blocks my step to go further for ftrace. > > Does ftrace guarantee that the replaced function is finished while > ftrace is replacing the functions? In the other word, is there a > possible that new function starts to run, while old function is also > running (maybe this function is called before replacing the function). No there is no such guarantee. That is up to the function callbacks to handle themselves. > > Function schedule_on_each_cpu maybe fails to excute, if there is no > enough memory to be allocated? Then kernel may be unstable, if ftrace > continues, without handling the error, does it? > > Previously, I posted a patch to fix this issue, and you nacked it. > > [PATCH] workqueue: Add the allocation flags to function > schedule_on_each_cpu_gfp Ah that patch. Actually __GFP_NOFAIL is pretty much deprecated. The real solution is to manually do the schedule on each CPU. I can whip up a patch for that. -- Steve -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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| From | Minfei Huang <mnfhuang@gmail.com> |
|---|---|
| Date | 2015-12-11 15:50 +0100 |
| Subject | Re: Some confusion about the period of updating new function in ftrace |
| Message-ID | <qExbc-5Nm-21@gated-at.bofh.it> |
| In reply to | #1289624 |
On 12/11/15 at 09:22P, Steven Rostedt wrote: > On Fri, 11 Dec 2015 18:52:42 +0800 > Minfei Huang <mnfhuang@gmail.com> wrote: > > > Hi, Steven. > > > > There is a confusion which blocks my step to go further for ftrace. > > > > Does ftrace guarantee that the replaced function is finished while > > ftrace is replacing the functions? In the other word, is there a > > possible that new function starts to run, while old function is also > > running (maybe this function is called before replacing the function). > > No there is no such guarantee. That is up to the function callbacks to > handle themselves. > Got it. > > > > Function schedule_on_each_cpu maybe fails to excute, if there is no > > enough memory to be allocated? Then kernel may be unstable, if ftrace > > continues, without handling the error, does it? > > > > Previously, I posted a patch to fix this issue, and you nacked it. > > > > [PATCH] workqueue: Add the allocation flags to function > > schedule_on_each_cpu_gfp > > Ah that patch. Actually __GFP_NOFAIL is pretty much deprecated. The > real solution is to manually do the schedule on each CPU. > > I can whip up a patch for that. Thanks for your explanation. Thanks Minfei -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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