> >> > > >> > + if (unlikely(sig == SIGQUIT || sig == SIGILL || sig == SIGTRAP > >> > || > >> > + sig == SIGABRT || sig == SIGBUS || sig == SIGFPE || > >> > + sig == SIGSEGV || sig == SIGXCPU || sig == SIGXFSZ || > >> > + sig == SIGSYS || sig == SIGSTKFLT)) > >> > + { > >> > + printk(KERN_WARNING "Sig %d send to %d owned by %d.%d > >> > (%s)\n", > >> > + sig, t->pid, t->uid, t->gid, t->comm); > >> > + } > >> > + > >> > /* > >> > * fast-pathed signals for kernel-internal things like SIGSTOP > >> > * or SIGKILL. > >> Would turning that into a switch() generate better code. > Yes, this time. > > >Doubt it: in the worst case you still nee to check for each possibility. > >Furthermore a.f.a.i.k. with switch you cannot do 'unlinkely()'. > > With if(), it generates a ton of "CMP, JE" instructions. > With switch(), I would assume gcc transforms it into using > a jump table (aka "JMP [table+sig]") > I tried it: with switch(), gcc transforms this into a > bitmap comparison ("MOV eax, 1; SHL eax, sig; TEST eax, 0x830109f8"), > which seems even cheaper than a jump table.
Ok, here's the new patch against 2.6.21.1: Signed-off by Folkert van Heusden <[EMAIL PROTECTED]> --- kernel/signal.c.org 2007-05-20 22:47:13.000000000 +0200 +++ kernel/signal.c 2007-05-20 22:54:17.000000000 +0200 @@ -739,6 +739,25 @@ struct sigqueue * q = NULL; int ret = 0; + /* emit some logging for nasty signals + * especially SIGSEGV and friends aught to be looked at when happening + */ + switch(sig) { + case SIGQUIT: + case SIGILL: + case SIGTRAP: + case SIGABRT: + case SIGBUS: + case SIGFPE: + case SIGSEGV: + case SIGXCPU: + case SIGXFSZ: + case SIGSYS: + case SIGSTKFLT: + printk(KERN_WARNING "Sig %d send to %d owned by %d.%d (%s)\n", + sig, t -> pid, t -> uid, t -> gid, t -> comm); + } + /* * fast-pathed signals for kernel-internal things like SIGSTOP * or SIGKILL. Folkert van Heusden -- MultiTail è uno flexible tool per seguire di logfiles e effettuazione di commissioni. Feltrare, provedere da colore, merge, 'diff-view', etc. http://www.vanheusden.com/multitail/ ---------------------------------------------------------------------- Phone: +31-6-41278122, PGP-key: 1F28D8AE, www.vanheusden.com - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/