| Message ID | 1482143832-11158-1-git-send-email-maninder1.s@samsung.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Mon, Dec 19, 2016 at 04:07:12PM +0530, Maninder Singh wrote: > prints can delay queuing of signal, so better to print > after force_sig_info. > > Let's say process generated SIGSEGV , and some other thread sends > SIGKILL to crashing process and it gets queued before SIGSEGV becuase > of little delay due to prints so in this case coredump might not generate. In any case, that's going to be a race - you can't predict exactly when the "other thread" will send the SIGKILL in relation to the SIGSEGV. So, I don't see the point of this change.
This is unreadable. Sorry. On Wed, Dec 21, 2016 at 05:59:11AM +0000, AMIT NAGAL wrote: > <HTML><HEAD> > <META content="text/html; charset=utf-8" http-equiv=Content-Type> > <STYLE id=mysingle_style type=text/css>.search-word { > BACKGROUND-COLOR: #ffee94 > } > P { > MARGIN-BOTTOM: 5px; FONT-SIZE: 10pt; FONT-FAMILY: Arial, arial; MARGIN-TOP: 5px > } > TD { > MARGIN-BOTTOM: 5px; FONT-SIZE: 10pt; FONT-FAMILY: Arial, arial; MARGIN-TOP: 5px > } > LI { > MARGIN-BOTTOM: 5px; FONT-SIZE: 10pt; FONT-FAMILY: Arial, arial; MARGIN-TOP: 5px > } > BODY { > FONT-SIZE: 10pt; FONT-FAMILY: Arial, arial > } > </STYLE> > > <META content=IE=5 http-equiv=X-UA-Compatible> > <META content=IE=5 http-equiv=X-UA-Compatible> > <STYLE id=knox_style type=text/css>P { > MARGIN-BOTTOM: 5px; FONT-SIZE: 10pt; FONT-FAMILY: Arial, arial; MARGIN-TOP: 5px > } > </STYLE> > > <META content=IE=5 http-equiv=X-UA-Compatible> > <META name=GENERATOR content="MSHTML 11.00.9600.18500"></HEAD> > <BODY> > <P></P> > <P>Hello,</P><PRE>On Mon, Dec 19, 2016 at 04:07:12PM +0530, Maninder Singh wrote: > >> prints can delay queuing of signal, so better to print > >>after force_sig_info. > >> > >> Let's say process generated SIGSEGV , and some other thread sends > >> SIGKILL to crashing process and it gets queued before SIGSEGV becuase > >> of little delay due to prints so in this case coredump might not generate. > > > In any case, that's going to be a race - you can't predict exactly when > > the "other thread" will send the SIGKILL in relation to the SIGSEGV. > > > So, I don't see the point of this change.</PRE><PRE>Actually SIGSEGV queueing gets delayed in __do_user_fault as logs are printed first(show_pte , show_regs).</PRE><PRE>meanwhile if SIGKILL gets queued , SIGSEGV wont be serviced first and coredump will be skipped . </PRE><PRE>so our intention is to queue the SIGSEGV as early as possible . so that the probability of race between</PRE><PRE>SIGKILL and SIGSEGV can be minimized .</PRE><PRE>Amit</PRE><PRE> </PRE><table id=bannersignimg><tr><td><div id="cafe-note-contents" style="margin:10px;font-family:Arial;font-size:10pt;"><p> </p></div></td></tr></table><table id=confidentialsignimg><tr><td><div id="cafe-note-contents" style="margin:10px;font-family:Arial;font-size:10pt;"><p><img unselectable="on" data-cui-image="true" style="display: inline-block; border: 0px solid; width: 520px; height: 144px;" src="cid:cafe_image_0@s-core.co.kr"><br></p></div></td></tr></table></BODY></HTML><img src='http://ext.samsung.net/m ail/ext/v1/external/status/update?userid=amit.nagal&do=bWFpbElEPTIwMTYxMjIxMDU1OTExZXBjbXM1cDExNDZjZWU5MjEyY2MxN2ZhOGQ1YjE4YzQ5YTA4NWRlZiZyZWNpcGllbnRBZGRyZXNzPWxpbnV4QGFybWxpbnV4Lm9yZy51aw__' border=0 width=0 height=0 style='display:none'>
diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c index 3a2e678..f92f90b 100644 --- a/arch/arm/mm/fault.c +++ b/arch/arm/mm/fault.c @@ -163,6 +163,15 @@ void show_pte(struct mm_struct *mm, unsigned long addr) { struct siginfo si; + tsk->thread.address = addr; + tsk->thread.error_code = fsr; + tsk->thread.trap_no = 14; + si.si_signo = sig; + si.si_errno = 0; + si.si_code = code; + si.si_addr = (void __user *)addr; + force_sig_info(sig, &si, tsk); + #ifdef CONFIG_DEBUG_USER if (((user_debug & UDBG_SEGV) && (sig == SIGSEGV)) || ((user_debug & UDBG_BUS) && (sig == SIGBUS))) { @@ -172,15 +181,6 @@ void show_pte(struct mm_struct *mm, unsigned long addr) show_regs(regs); } #endif - - tsk->thread.address = addr; - tsk->thread.error_code = fsr; - tsk->thread.trap_no = 14; - si.si_signo = sig; - si.si_errno = 0; - si.si_code = code; - si.si_addr = (void __user *)addr; - force_sig_info(sig, &si, tsk); } void do_bad_area(unsigned long addr, unsigned int fsr, struct pt_regs *regs) diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c index a78a5c4..eb5d0e3 100644 --- a/arch/arm64/mm/fault.c +++ b/arch/arm64/mm/fault.c @@ -197,14 +197,6 @@ static void __do_user_fault(struct task_struct *tsk, unsigned long addr, { struct siginfo si; - if (unhandled_signal(tsk, sig) && show_unhandled_signals_ratelimited()) { - pr_info("%s[%d]: unhandled %s (%d) at 0x%08lx, esr 0x%03x\n", - tsk->comm, task_pid_nr(tsk), fault_name(esr), sig, - addr, esr); - show_pte(tsk->mm, addr); - show_regs(regs); - } - tsk->thread.fault_address = addr; tsk->thread.fault_code = esr; si.si_signo = sig; @@ -212,6 +204,14 @@ static void __do_user_fault(struct task_struct *tsk, unsigned long addr, si.si_code = code; si.si_addr = (void __user *)addr; force_sig_info(sig, &si, tsk); + + if (unhandled_signal(tsk, sig) && show_unhandled_signals_ratelimited()) { + pr_info("%s[%d]: unhandled %s (%d) at 0x%08lx, esr 0x%03x\n", + tsk->comm, task_pid_nr(tsk), fault_name(esr), sig, + addr, esr); + show_pte(tsk->mm, addr); + show_regs(regs); + } } static void do_bad_area(unsigned long addr, unsigned int esr, struct pt_regs *regs)