Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751501AbbKYRXP (ORCPT ); Wed, 25 Nov 2015 12:23:15 -0500 Received: from mail-wm0-f51.google.com ([74.125.82.51]:33731 "EHLO mail-wm0-f51.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750768AbbKYRW7 (ORCPT ); Wed, 25 Nov 2015 12:22:59 -0500 Subject: Re: [PATCH v5 7/7] usb: gadget: f_midi: pre-allocate IN requests To: Clemens Ladisch , linux-usb@vger.kernel.org References: <1447177929-22252-1-git-send-email-eu@felipetonello.com> <1447177929-22252-8-git-send-email-eu@felipetonello.com> <5645A58F.9030902@ladisch.de> Cc: linux-kernel@vger.kernel.org, Felipe Balbi , Greg Kroah-Hartman , Robert Baldyga From: Felipe Ferreri Tonello X-Enigmail-Draft-Status: N1111 Message-ID: <5655EE70.8040502@felipetonello.com> Date: Wed, 25 Nov 2015 17:22:56 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.3.0 MIME-Version: 1.0 In-Reply-To: <5645A58F.9030902@ladisch.de> Content-Type: multipart/mixed; boundary="------------010104050105000604060605" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 11180 Lines: 230 This is a multi-part message in MIME format. --------------010104050105000604060605 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 8bit Hi Clemens On 13/11/15 08:55, Clemens Ladisch wrote: > Felipe F. Tonello wrote: >> This patch introduces pre-allocation of IN endpoint USB requests. This >> improves on latency (requires no usb request allocation on transmit) and avoid >> several potential probles on allocating too many usb requests (which involves >> DMA pool allocation problems). >> >> This implementation also handles better multiple MIDI Gadget ports, always >> processing the last processed MIDI substream if the last USB request wasn't >> enought to handle the whole stream. > >> ... >> +++ b/drivers/usb/gadget/function/f_midi.c >> @@ -88,6 +89,9 @@ struct f_midi { >> int index; >> char *id; >> unsigned int buflen, qlen; >> + DECLARE_KFIFO_PTR(in_req_fifo, struct usb_request *); >> + unsigned int in_req_num; >> + unsigned int in_last_port; > > As far as I can see, in_req_num must always have the same value as qlen. Yes, I've removed in_req_num. > >> @@ -366,6 +388,20 @@ static void f_midi_disable(struct usb_function *f) >> + while (!kfifo_is_empty(&midi->in_req_fifo)) { >> + ... >> + len = kfifo_get(&midi->in_req_fifo, &req); >> + if (len == 1) >> + free_ep_req(midi->in_ep, req); >> + else >> + ERROR(midi, "%s couldn't free usb request: something went wrong with kfifo\n", >> + midi->in_ep->name); >> + } > > kfifo_get() already checks for the FIFO being empty, so you can just > drop kfifi_is_empty(). Ok. I've simplified this code. I wasn't really happy with it either. > >> @@ -487,57 +523,111 @@ static void f_midi_transmit_byte(struct usb_request *req, >> ... >> +static void f_midi_transmit(struct f_midi *midi) >> +{ >> +... >> + len = kfifo_peek(&midi->in_req_fifo, &req); >> + ... >> + if (req->length > 0) { >> + WARNING(midi, "%s: All USB requests have been used. Current queue size " >> + "is %u, consider increasing it.\n", __func__, midi->in_req_num); >> + goto drop_out; >> + } > > There are two cases where the in_req FIFO might overflow: > 1) the gadget is trying to send too much data at once; or > 2) the host does not bother to read any of the data. > > In case 1), the appropriate action would be to do nothing, so that the > remaining data is sent after some currently queued packets have been > transmitted. In case 2), the appropriate action would be to drop the > data (even better, the _oldest_ data), and spamming the log with error > messages would not help. True. In this case the log will be spammed. How would you suggest to drop the oldest data? That doesn't really seem to be feasible. > > This code shows the error message for case 1), but does the action for > case 2). > > I'm not quite sure if trying to detect which of these cases we have is > possible, or worthwhile. Anyway, with a packet size of 64, the queue > size would be 32*64 = 2KB, which should be enough for everyone. So I > propose to ignore case 1), and to drop the error message. Agree. It would be useful for users to know about case 1), but like you said it is probably not worthwhile to do to so. > >> @@ -1130,6 +1222,12 @@ static struct usb_function *f_midi_alloc(struct usb_function_instance *fi) >> + if (kfifo_alloc(&midi->in_req_fifo, midi->qlen, GFP_KERNEL)) >> + goto setup_fail; > > The setup_fail code expects an error code in the status variable. Done. Felipe --------------010104050105000604060605 Content-Type: application/pgp-keys; name="0x92698E6A.asc" Content-Transfer-Encoding: quoted-printable Content-Disposition: attachment; filename="0x92698E6A.asc" -----BEGIN PGP PUBLIC KEY BLOCK----- Version: GnuPG v2 mQINBFYedIcBEACVKGKoEjb3zlvAz5SUvBej7Sx13BPd8hVulQD+mqjfuRFPmZA5 LBXPX1zTRWwGEbbZegP3tLfKP+XekzO6BQhDihMmKuRusdgDsdMtldwhjHuUwKn7 kxB2k79jSG802lAjIv2l5hijOfKIGTATKwiMijuXho54DGltIgNyN/Onwk9HnM6d jsV5uubaI468JRH6j8HXXievo24BDvsimIE75ImiM53ruiwPwEry1hi1CnE5OpqG oe/lt27+nLXijfNZOpBZ3Q+RPVBdqPTkMlBJAa4sg+qwZoSMvQJFAGROiJ7+ICCW O4GPMrAn8CRcCI9ENKBj2dQ4bBEP1a+f16GNMUUU37wocqtyNHo0Pa/DnFh91kcu /2dvUX4XPeEimEoSKroRLOXC9RGSFYB/r9UXqFgbmyQ4TZLx0mAWIjoUQtbIJNRz Pt46UeznCVLJTg7CzIvtv8vwmMFvaepr8ONoZn+tpX8VW4dgzsMZDrVspE0Vg3oo K9JRi1nN3GcJJK4zG2ShvEkPffRHuBuyX5wR8MPRYTShKnJR5qd1cCSK73fCv4DP bjywmGjucqcLiyYbByjmHaqzRaKJclmT/jhs6qZHs+pVLkmHkHdf/WLP6Xgcvmo8 c+SATrJwRsyW9riyMB7uNg3T84umbQrl00nAhcq73rem/602H+Qrh8rEfQARAQAB tC1GZWxpcGUgRmVycmVyaSBUb25lbGxvIDxldUBmZWxpcGV0b25lbGxvLmNvbT6J AjwEEwEIACYCGyMHCwkIBwMCAQYVCAIJCgsEFgIDAQIeAQIXgAIZAQUCVlXsdwAK CRDMRLTQkmmOapJFD/9XZZdX5XdXrQ2Qr7znQCOMPfOFiTqK8A1vVJPfLcPdkDyW iDfV2w4jyxKjgkcO8hgjZWAGdXhKxEXt8bQIZ+Po3eOqKo/O69+WyYS33uAKfNbr t4BcJOM2Vh2MwTymzh5EKjsKi/vmqFqvcpa81Jc4exDaHhb2mqMW8DZc96nMPwij +Z4vVooOVt5DVGeG4o2rztoti+KaXys6nycm8ErMmqWmL0viEnXHDRTOUHpnhEQY Vlg+hfxYrk00DphAePrpRp/HaxNncxR+ID0SHmYlLCaEy7s5ksOORjlKSk+7Nqat X69ymfXeEI84ror11IR7kuAA+rkhHMacWXANPkXtuEBi9Nl3V5Rvud4f/RL3Sh2x lwPfxca9rIR/7JYwoCzQ8iORok3VqKOtpufLKMsIl9sdj7ZxI6f6tZDm5uAaCZAt f15EcGiVWZgGdKlXzIWFkUsdRhtGYEQBF1Li/qLrnoS5T32eSCt8cgJlkDyKqNbX fxvV0KON8tJ9jBnMmoADetF/9V3A6EIBtTdxsz+UKjk6PV0bx398AbdvNB22r6Kw n1E2ZqzfNIaAOv5lEHh7VP7+s3vdXcKfnfobW0qd56NpAGTPhAN00wl7T5oMN3xS MNTPIC4316E8KChA5CQ3h6RRlZYvAJx7QWfJKX5zb8EVcJb0ul67V8hn1h/s54kC PwQTAQgAKQUCVh50hwIbIwUJCWYBgAcLCQgHAwIBBhUIAgkKCwQWAgMBAh4BAheA AAoJEMxEtNCSaY5qHxAP/0LmkXtaZvFelixfYibDHwpz+62mWydYN8I13ikV7uK0 DxpN6W3SeoAY6mF6mwHKyhsNhlOYPR8Rb+CpJxjIez6sPHAA02m4HqfTiNRuAeLM hSpiMIVesGgR9Lt/2gnCcF/R/pNJd5RC7wWzeeiS9/b2XtFImRSFvctyHwGXLBYM nlRx/o34kWscTCqixBF7lm3umAErDUd0fvL4oV2sC3W8Ncjfk/WQWfschV50lNtO h1Imvt+5ud3AJEcwXew0pbHKHvtrVc7toIO3jhZypD9YXP3aR9ZEkHS/bnd5HRHV t3iEwXH+bNu/evEB5dQcSf6M6Bwt7Ty2fqFx2PUmnZ22W4HGelPmE5aCqkBQqAkR kBmPEPlUIz6GLoj8jUL1ey+T+oCyD5wZoVb841bJDKIPxAa+P+MjFtQUpSXgyi8x G0Ic10pK9u3xsu5xzqLoAwt+pK+oxeWrZhJXg9/MFmqQQTX2dH8lIrgIOsHis5uK ySohiPwYQ0HUbbSFB9wM6e5dq621RvOkMA/myFtdjJX+Ynr7FmIpIZQiWZvOv0nM 0CeF7MotMIVa1ioh9K6/Z5WLjTBQh32DrGL07H0h+SMOvcL1IJuw9aG5qDKH4VW9 VSbHAogVSntamVrCg8jcT8uxEtwZNZH3aBqoYv4pa4MJsIs6vI0/9Y/mVyYVhQPN tDFGZWxpcGUgRmVycmVyaSBUb25lbGxvIDxmZWxpcGUudG9uZWxsb0BnbWFpbC5j b20+iQI5BBMBCAAjAhsjBwsJCAcDAgEGFQgCCQoLBBYCAwECHgECF4AFAlZV7HoA CgkQzES00JJpjmqexA//UHC0P+5NMN0HS0EC3vqdf+9AFfX/Gx+q6BjlaYh8gkGI 5SNGGb25dooGBRhXzFvp5UmxQjngvZO0Jl071kbqOs7IylZWvUB0tIB/9kcvIgJM U13CvdD2XwHDgKoCCS07ymFd9j31FhfYK6eRpr72oGHtjhGOSIj1u8T/4mJDstoc zK39gZjTQjzT/2sDbr2sd41KLJ9Ly3H67EgoxYIAQQwwT1Z7x88a8BORIXS8iZPw z3D8A1r2BT55qukwEP7GktNArKlhrieFRHCxk8PAtZRj8TrOEyG9nnuZWZQWcb6M suIY6s4cyL5KRTUgGfnpc+VMcNKnm0WmKg5jZXRFwg0DECZi0wJqsS8GPrq4La+K laxPcXj3ShJePj0YuTcJ/fPYoqqelcbmlqg6m+S9s8PRKPzlESt2jYPbgqMzE0Lu DLRGT7SBYgHgDVFwIuFyHQaqEhnU/nLWmyMSuTOE5L4s/CR1xY4qQUtOTnDFbwqL 125kbOCiRSMBBMOB4Q+UW3+dJ7uqo6LSqIKa/LWvzRmn5po4iSHAD18ivOh1wTe6 0d/ngjzpTm80uFrwfgkQTexxESYjlBbceBC8kpb1zPFrip41hIi3iPP9UQnnpOO2 hDrQu5z0N8HMIFg3kciR22wUMzQnyVN4iKfkrhERjjuYWOXJmC5I76DBqlEKLCWJ Aj8EEwEIACkFAlYyWW0CGyMFCQlmAYAHCwkIBwMCAQYVCAIJCgsEFgIDAQIeAQIX gAAKCRDMRLTQkmmOakxGD/4xoYnRMuy8m6IwT1Y6mWzXZMkcClxwisUkwgF37jMR Xk7aitPqlD7AOn/jzKZBmKqOokyH3Y65u/AV6O7jXWWM3Ru0fDYYt0RZR0CkE0c2 Rio64ol6GWnF4dIiyTTSyxBNadVJXRYBpp5G78ie495ZOp35WUoz2RhExeIQGkBb ++UIyCh3eK70PPJ+1/dDV9sSRncIBZLSv+4hc4gS6YoprtSgiS8sdf8uBVtjT3r0 nmrKfTpktADqOOACd/K3LIdf6rlvAYsuWdQ/q32MF7Clrlpt9e5oqi+ASJcLNWUz cT8nFyvjJzM5kQEBblT6uzyWE5N6+K/t23Uw13vSx3Z2uhhfRQjcSOcZgHdvc8w1 3UXhE+XRCMmtA7jonJuFLYOXbjeeNEbJj5ManrOQMSnVy+kRlf3pLoc7VjJGd2k9 w1U+62b1IVypQCoDNhIy3YTjw7D151z/i5tK5yBvntswji10InowqPRuvt3C3fpW kv2MnB6qI+u6M5bP/1CvkLSC9vX+gavUFYZ/wCESVrl1FYQPfOoEgvEId9Ajzx0B qyR/5jXY3ZzWhnXNtYpHXy5/mJdvZ+v5ra5JLWKVA3pa+QbTd3v6ELo9NKavylcD FX9X2l2s7kp/FRVUZg3mr/3Pf0R1EFZAwM2Fgb5iKPLPjGi4b4sVtMxeXfbXRMBf 5rQwRmVsaXBlIEZlcnJlcmkgVG9uZWxsbyA8ZmVsaXBlLnRvbmVsbG9Acm9saS5j b20+iQI5BBMBCAAjAhsjBwsJCAcDAgEGFQgCCQoLBBYCAwECHgECF4AFAlZV7HoA CgkQzES00JJpjmrkTA//YiyBcGn+hjsKsVxFHseUw0ygN7TDLGeG7z0sP7AybVXR h4AwVcqyNkJjJ1UPXxPm5ra6/TbJf3XEalhIJtqh0MI0p+NQTFVOcGG58e6oMWj1 yBHAPmCyMJCi3GrB1/weP3qMiCdKWOWjxt+NoWss3pqqpSKHGW2rgmM3VP60iheR uZDDDI9DtoDz1ePT2AQZnopez2k75syZix1zkAI/VM/T3Y5lcnbaO4C+akDusfN0 galjwveYPIv6bBY6gd3B/7leSe2l4M3VIahj/1e4R2aLB78/pyy5BaI47zprkzPF zOAtZTurrwnE/1s3qWMP3OFeKiD1NLCm8kkvVakk/FjG8avFTAB3idNjpRT3wyPp nGv3G5Bp2jII35l7L5e2/zGcIigDNAUtdL3IgszfqtTVwGgISZDoxHIyBucqpYqV +ZesP1CpvyXaG4ME1QNTYZcVj1VTtz97IwntHw51r0d4IXjTbbrwJYR/g15XqNRB HwQyumPr3kMXLKTHCroK0z1OoT+pwNAO/XEWqQ5NQwyjalkFa1PzSPgcbTH46gs+ lilkrSgDuj/Amt0pkBSadgviJhsq2nQU49E8OOrrgDab0Z+6ur2lTENPWD4U9PS1 PisVd3ZAm8WmLx1ZktMgv2IPS9Tm+HlIdTPcw8OY12iPP1tRcE7pu23HLP3Un++0 KEZlbGlwZSBGZXJyZXJpIFRvbmVsbG8gPGZlbGlwZUByb2xpLmNvbT6JAjkEEwEI ACMCGyMHCwkIBwMCAQYVCAIJCgsEFgIDAQIeAQIXgAUCVlXsegAKCRDMRLTQkmmO aoymD/94mkk+RCXUQI6i3Z5qfenWHaJF86SH1tekpJl3eFHEUji0JWICOWS9225E 3oBbLDAA3szFWFxXNA2JdOv0ljwqWHT/aRXJlQ19LHMItguUyxfoELf818aym8bL MtazXRrYTy71SfvJwIleMYrNeodZnC4GwSOaKz5Rh/Qbnfzz/wG4dCNtGTcQ+EKP vcA06bNbYaqGA+qtrZ3st3lEmz/OPqRox7LqZTs/fvdAo49F8BlTZ6p09s2u7wVF UfYbi4+PQonGpn47QTx41OjFzzeA3NnCDak6JuSYa92QznShP0b03G5g4LdonwbU P/ivpzkSdWYVNwp/a7GfuhBAyk2VP/StF6WzzGC0j4TyBx+H5RzU32brNNsye1bL 8AMvHl9C3BEdgLnIlsTRMRCjs7f4EoFyEzmW40FUXPaJzxF6bCY/+GzDIhtMisjK fUFyakHnjITZSjo7Wqhp3W6a64esqPFbuFoX7sp5mWYzqDuKy0yD7S9vjA8wLdCt usBRw6TvVhaxmnOOa8zkyhOLqJ6le+zw8mW+Cot4LFFkeXyySNyRbrqOx3JqezRc olouAh2AJEir2sW3kdP53xRwUE5CJogC2QPuGSl5T1pcARmQJmudco2dk7C+hriF hkCHjp5ue9evv6u/Z7m+AcPJguVlq21ynYRrTeFJXCd2rgkAWbkCDQRWHnSHARAA yrLAhPO4JiqRk2sem+8bweimfnKmIm+ttTqjDni1DdBKtCZFUxPwEKzuOpU4aals 9Ohk4rQMnm6Q2XaJxIs0lijQJjVFbExtm9G2R2gkPJ5fnk4+k2mvps5F/iJjQk0k zWMITEA6cJzt9B8YC4dfsIq3lhCInOvSMBIVtDapruDGU4OskFBiKfzIq8diq/Ep qNfwCxZX2IcPhFv2+SJjph60oUC4WJ4zgINfJWdUGlIZrQp8sr/aEa77BVtLnTsu MHwqOF7P7yk4qpb3EFuyNCsJVAirYTqZeMWEv/pYiwtAgYOewdwptP8+5lbcXAor Y8Cs0GdW0r7LUzQjfhXl67EQWJuvGDBKMQ35LyUJtOm5m+qAnalz9Eyb0xRc9Arl rzH2GfCIr4ga+2RPw7fq7fZcbBcJDs770Mz0kVrLv3IAcc6fmnvuo30TFeIPB62/ c4xIe8njJ8RxbfwYAtd2KoAzwRQEqJQECyNnqENFHj2cimEueXf7NAw+z1nl1HIl 7MrHUeA0FQTw4WdGCahTuFRaJCjmODmKCFAooDWEek6jwNv18hCDJytSDc7uLAvH D2b9Sd40P1V2ochSf/DS/osfEIEeBf5mkG/MHBBbNxvSGP1h2yUM5C7g4nc6B+nz 5bIULhw0ojZx+U1i63gJkMsVMjKDAa+mGsWu0vAI3v0AEQEAAYkCHwQYAQgACQIb DAUCVlXsegAKCRDMRLTQkmmOao4vD/9GYLw5VmydK5BJ0sX12QmR7oMK4skMkcg/ gofkJ6njI4ETDG/pQfgBSQ/P0gUMXmhHgmpaRgs0tkS2NwsvURianXiQNpJwUA2g qKngqWlEvGOVkgOw7JKpdLWBvEW4vfP0Z0Q9brdeQG//9T9xyoyTC/jPM9A33NtI KlexBfBT7lXBy/y4tqf96KTOXk3STmI6nmSwmpPPtjxXXGQiMExGxAru+VX0HFxi JBS2fw/ucluVk2kffAO0y7DTL0UH3IWq4wEtHJQlEcujmUkP8PJSVIkhJpNlppR2 97DVxLcMAbnyxCW+ms1lCuZ5KB98KtowipqY9jhAPeP06W2WikENdmpLfNHhyIaM NKF7J+4zqPda7jZN1aKqs5OguJ4V82xXRJ0O6qSAd3Kvwi3MaKtNAv09JFG7UIcK ALJ+OQBzc00z54ii19ZPHjER6cYmcVutBUGOssqtyCOZymVbc7VYecdjxVrLwdDp LHHpcIjFn5ADjIAwGlt5ttkPvFTmqLeSWG9+vtoBShzQdeKJ4AN4r6/for/XsmF4 Jf7qGK8RamVX8lpWaNjUGtVSUOMTaSR1pmQJERDO2/WEZCm5hUFkYDbu+h+9m1W+ KL2ZkyGRC8FoZ46ly1J8koEeEoa57Au/uyK3KyvzlXuCI5zgGE+TohIjOr6d3TN4 SkAyCfQaSw=3D=3D =3DJwBB -----END PGP PUBLIC KEY BLOCK----- --------------010104050105000604060605-- -- 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/