Messages in this thread | | | Subject | Re: [PATCH v1] scsi: Don't select SCSI_PROC_FS by default | From | Douglas Gilbert <> | Date | Tue, 18 Jun 2019 11:31:42 -0400 |
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On 2019-06-18 3:29 a.m., Marc Gonzalez wrote: > On 18/06/2019 03:08, Finn Thain wrote: > >> On Mon, 17 Jun 2019, Douglas Gilbert wrote: >> >>> On 2019-06-17 5:11 p.m., Bart Van Assche wrote: >>> >>>> On 6/12/19 6:59 AM, Marc Gonzalez wrote: >>>> >>>>> According to the option's help message, SCSI_PROC_FS has been >>>>> superseded for ~15 years. Don't select it by default anymore. >>>>> >>>>> Signed-off-by: Marc Gonzalez <marc.w.gonzalez@free.fr> >>>>> --- >>>>> drivers/scsi/Kconfig | 3 --- >>>>> 1 file changed, 3 deletions(-) >>>>> >>>>> diff --git a/drivers/scsi/Kconfig b/drivers/scsi/Kconfig >>>>> index 73bce9b6d037..8c95e9ad6470 100644 >>>>> --- a/drivers/scsi/Kconfig >>>>> +++ b/drivers/scsi/Kconfig >>>>> @@ -54,14 +54,11 @@ config SCSI_NETLINK >>>>> config SCSI_PROC_FS >>>>> bool "legacy /proc/scsi/ support" >>>>> depends on SCSI && PROC_FS >>>>> - default y >>>>> ---help--- >>>>> This option enables support for the various files in >>>>> /proc/scsi. In Linux 2.6 this has been superseded by >>>>> files in sysfs but many legacy applications rely on this. >>>>> - If unsure say Y. >>>>> - >>>>> comment "SCSI support type (disk, tape, CD-ROM)" >>>>> depends on SCSI >>>> >>>> Hi Doug, >>>> >>>> If I run grep "/proc/scsi" over the sg3_utils source code then grep reports >>>> 38 matches for that string. Does sg3_utils break with SCSI_PROC_FS=n? >>> >>> First, the sg driver. If placing >>> #undef CONFIG_SCSI_PROC_FS >>> >>> prior to the includes in sg.c is a valid way to test that then the >>> answer is no. Ah, but you are talking about sg3_utils . >>> >>> Or are you? For sg3_utils: >>> >>> $ find . -name '*.c' -exec grep "/proc/scsi" {} \; -print >>> static const char * proc_allow_dio = "/proc/scsi/sg/allow_dio"; >>> ./src/sg_read.c >>> static const char * proc_allow_dio = "/proc/scsi/sg/allow_dio"; >>> ./src/sgp_dd.c >>> static const char * proc_allow_dio = "/proc/scsi/sg/allow_dio"; >>> ./src/sgm_dd.c >>> static const char * proc_allow_dio = "/proc/scsi/sg/allow_dio"; >>> ./src/sg_dd.c >>> "'echo 1 > /proc/scsi/sg/allow_dio'\n", q_len, dirio_count); >>> ./testing/sg_tst_bidi.c >>> static const char * proc_allow_dio = "/proc/scsi/sg/allow_dio"; >>> ./examples/sgq_dd.c >>> >>> >>> That is 6 (not 38) by my count. Those 6 are all for direct IO >>> (see below) which is off by default. I suspect old scanning >>> utilities like sg_scan and sg_map might also use /proc/scsi/* . >>> That is one reason why I wrote lsscsi. However I can't force folks >>> to use lsscsi. As a related example, I still get bug reports for >>> sginfo which I inherited from Eric Youngdale. >>> >>> If I was asked to debug a problem with the sg driver in a >>> system without CONFIG_SCSI_PROC_FS defined, I would decline. >>> >>> The absence of /proc/scsi/sg/debug would be my issue. Can this >>> be set up to do the same thing: >>> cat /sys/class/scsi_generic/debug >>> Is that breaking any sysfs rules? >>> >>> >>> Also folks who rely on this to work: >>> cat /proc/scsi/sg/devices >>> 0 0 0 0 0 1 255 0 1 >>> 0 0 0 1 0 1 255 0 1 >>> 0 0 0 2 0 1 255 0 1 >>> >>> would be disappointed. Further I note that setting allow_dio via >>> /proc/scsi/sg/allow_dio can also be done via /sys/module/sg/allow_dio . >>> So that would be an interface breakage, but with an alternative. >> >> You can grep for /proc/scsi/ across all Debian packages: >> https://codesearch.debian.net/ >> >> This reveals that /proc/scsi/sg/ appears in smartmontools and other >> packages, for example. > > Hello everyone, > > Please note that I am _in no way_ suggesting that we remove any code. > > I just think it might be time to stop forcing CONFIG_SCSI_PROC_FS into > every config, and instead require one to explicitly request the aging > feature (which makes CONFIG_SCSI_PROC_FS show up in a defconfig). > > Maybe we could add CONFIG_SCSI_PROC_FS to arch/x86/configs/foo ? > (For which foo? In a separate patch or squashed with this one?)
Marc, Since current sg driver usage seems to depend more on SCSI_PROC_FS being "y" than other parts of the SCSI subsystem then if SCSI_PROC_FS is to default to "n" in the future then a new CONFIG_SG_PROC_FS variable could be added.
If CONFIG_CHR_DEV_SG is "*" or "m" then default CONFIG_SG_PROC_FS to "y"; if CONFIG_SCSI_PROC_FS is "y" then default CONFIG_SG_PROC_FS to "y"; else default CONFIG_SG_PROC_FS to "n". Obviously the sg driver would need to be changed to use CONFIG_SG_PROC_FS instead of CONFIG_SCSI_PROC_FS .
Does that defeat the whole purpose of your proposal or could it be seen as a partial step in that direction? What is the motivation for this proposal?
Doug Gilbert
BTW We still have the non-sg related 'cat /proc/scsi/scsi' usage and 'cat /proc/scsi/device_info'. And I believe the latter one is writable even though its permissions say otherwise.
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