Turn console printf buffering into a kernel option and only on
by default for sun4v where it is absolutely required. This change moves the buffer from struct pcpu to the stack to avoid using the critical section which created a LOR in a couple of cases due to interaction with the tty code and kqueue. The LOR can't be fixed with the critical section and the pcpu buffer can't be used without the critical section. Putting the buffer on the stack was my initial solution, but it was pointed out that the stress on the stack might cause problems depending on the call path. We don't have a way of creating tests for those possible cases, so it's best to leave this as an option for the time being. In time we may get enough data to enable this option more generally.
This commit is contained in:
parent
b3ef1381d4
commit
e0b651251d
Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=164760
@ -185,7 +185,6 @@ ASSYM(PC_CURTHREAD, offsetof(struct pcpu, pc_curthread));
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ASSYM(PC_FPCURTHREAD, offsetof(struct pcpu, pc_fpcurthread));
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ASSYM(PC_IDLETHREAD, offsetof(struct pcpu, pc_idlethread));
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ASSYM(PC_CURPCB, offsetof(struct pcpu, pc_curpcb));
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ASSYM(PC_CONS_BUFR, offsetof(struct pcpu, pc_cons_bufr));
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ASSYM(PC_CPUID, offsetof(struct pcpu, pc_cpuid));
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ASSYM(PC_SCRATCH_RSP, offsetof(struct pcpu, pc_scratch_rsp));
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ASSYM(PC_CURPMAP, offsetof(struct pcpu, pc_curpmap));
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@ -69,7 +69,6 @@ ASSYM(PCB_R12, offsetof(struct pcb, un_32.pcb32_r12));
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ASSYM(PCB_PC, offsetof(struct pcb, un_32.pcb32_pc));
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ASSYM(PCB_SP, offsetof(struct pcb, un_32.pcb32_sp));
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ASSYM(PC_CONS_BUFR, offsetof(struct pcpu, pc_cons_bufr));
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ASSYM(PC_CURPCB, offsetof(struct pcpu, pc_curpcb));
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ASSYM(PC_CURTHREAD, offsetof(struct pcpu, pc_curthread));
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ASSYM(M_LEN, offsetof(struct mbuf, m_len));
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@ -709,6 +709,9 @@ SC_PIXEL_MODE opt_syscons.h
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SC_RENDER_DEBUG opt_syscons.h
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SC_TWOBUTTON_MOUSE opt_syscons.h
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# options for printf
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PRINTF_BUFR_SIZE opt_printf.h
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# kbd options
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KBD_DISABLE_KEYMAP_LOAD opt_kbd.h
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KBD_INSTALL_CDEV opt_kbd.h
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@ -195,7 +195,6 @@ ASSYM(PC_COMMON_TSSD, offsetof(struct pcpu, pc_common_tssd));
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ASSYM(PC_TSS_GDT, offsetof(struct pcpu, pc_tss_gdt));
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ASSYM(PC_FSGS_GDT, offsetof(struct pcpu, pc_fsgs_gdt));
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ASSYM(PC_CURRENTLDT, offsetof(struct pcpu, pc_currentldt));
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ASSYM(PC_CONS_BUFR, offsetof(struct pcpu, pc_cons_bufr));
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ASSYM(PC_CPUID, offsetof(struct pcpu, pc_cpuid));
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ASSYM(PC_CURPMAP, offsetof(struct pcpu, pc_curpmap));
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ASSYM(PC_PRIVATE_TSS, offsetof(struct pcpu, pc_private_tss));
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@ -38,6 +38,7 @@
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__FBSDID("$FreeBSD$");
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#include "opt_ddb.h"
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#include "opt_printf.h"
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#include <sys/param.h>
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#include <sys/systm.h>
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@ -291,18 +292,24 @@ printf(const char *fmt, ...)
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va_list ap;
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struct putchar_arg pca;
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int retval;
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critical_enter();
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#ifdef PRINTF_BUFR_SIZE
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char bufr[PRINTF_BUFR_SIZE];
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#endif
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va_start(ap, fmt);
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pca.tty = NULL;
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pca.flags = TOCONS | TOLOG;
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pca.pri = -1;
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pca.p_bufr = (char *) PCPU_PTR(cons_bufr);
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#ifdef PRINTF_BUFR_SIZE
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pca.p_bufr = bufr;
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pca.p_next = pca.p_bufr;
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pca.n_bufr = PCPU_CONS_BUFR;
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pca.remain = PCPU_CONS_BUFR;
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pca.n_bufr = sizeof(bufr);
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pca.remain = sizeof(bufr);
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*pca.p_next = '\0';
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#else
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/* Don't buffer console output. */
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pca.p_bufr = NULL;
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#endif
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retval = kvprintf(fmt, putchar, &pca, 10, ap);
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va_end(ap);
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@ -314,8 +321,6 @@ printf(const char *fmt, ...)
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if (!panicstr)
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msgbuftrigger = 1;
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critical_exit();
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return (retval);
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}
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@ -324,17 +329,23 @@ vprintf(const char *fmt, va_list ap)
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{
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struct putchar_arg pca;
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int retval;
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critical_enter();
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#ifdef PRINTF_BUFR_SIZE
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char bufr[PRINTF_BUFR_SIZE];
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#endif
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pca.tty = NULL;
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pca.flags = TOCONS | TOLOG;
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pca.pri = -1;
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pca.p_bufr = (char *) PCPU_PTR(cons_bufr);
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#ifdef PRINTF_BUFR_SIZE
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pca.p_bufr = bufr;
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pca.p_next = pca.p_bufr;
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pca.n_bufr = PCPU_CONS_BUFR;
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pca.remain = PCPU_CONS_BUFR;
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pca.n_bufr = sizeof(bufr);
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pca.remain = sizeof(bufr);
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*pca.p_next = '\0';
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#else
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/* Don't buffer console output. */
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pca.p_bufr = NULL;
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#endif
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retval = kvprintf(fmt, putchar, &pca, 10, ap);
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@ -345,8 +356,6 @@ vprintf(const char *fmt, va_list ap)
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if (!panicstr)
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msgbuftrigger = 1;
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critical_exit();
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return (retval);
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}
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@ -55,7 +55,6 @@
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#include <machine/pmap.h>
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#include <machine/sigframe.h>
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ASSYM(PC_CONS_BUFR, offsetof(struct pcpu, pc_cons_bufr));
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ASSYM(PC_CURTHREAD, offsetof(struct pcpu, pc_curthread));
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ASSYM(PC_CURPCB, offsetof(struct pcpu, pc_curpcb));
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ASSYM(PC_CURPMAP, offsetof(struct pcpu, pc_curpmap));
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@ -198,7 +198,6 @@ ASSYM(HASH_ENTRY_SHIFT, HASH_ENTRY_SHIFT);
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ASSYM(V_INTR, offsetof(struct vmmeter, v_intr));
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ASSYM(PC_CONS_BUFR, offsetof(struct pcpu, pc_cons_bufr));
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ASSYM(PC_CURTHREAD, offsetof(struct pcpu, pc_curthread));
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ASSYM(PC_CURPCB, offsetof(struct pcpu, pc_curpcb));
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ASSYM(PC_CPUID, offsetof(struct pcpu, pc_cpuid));
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@ -59,6 +59,7 @@ options _KPOSIX_PRIORITY_SCHEDULING # POSIX P1003_1B real-time extensions
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options AHC_REG_PRETTY_PRINT # Print register bitfields in debug
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# output. Adds ~128k to driver.
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options ADAPTIVE_GIANT # Giant mutex is adaptive.
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options PRINTF_BUFR_SIZE=128 # Prevent printf output being interspersed.
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# Debugging for use in -current
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options KDB # Enable kernel debugger support.
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@ -48,9 +48,6 @@
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struct pcb;
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struct thread;
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/* Size of the per-cpu console buffer for printf(). */
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#define PCPU_CONS_BUFR 128
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/*
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* This structure maps out the global data that needs to be kept on a
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* per-cpu basis. The members are accessed via the PCPU_GET/SET/PTR
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@ -74,8 +71,6 @@ struct pcpu {
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int pc_ktr_idx; /* Index into trace table */
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char *pc_ktr_buf;
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#endif
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char pc_cons_bufr[PCPU_CONS_BUFR];
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/* Console buffer */
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PCPU_MD_FIELDS;
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struct vmmeter pc_cnt; /* VM stats counters */
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struct device *pc_device;
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